kmsdrm: Make this build with significantly older system libraries.

This allows one to build Raspberry Pi versions on an ancient version of
Raspbian and get both the KMSDRM and RPI video targets built into SDL, giving
maximum binary compatibility from linking against an older glibc, etc, but
also making one library that can access video on all RPi models and OS
releases.

configure

@@ -21987,12 +21987,12 @@ if test -n "$LIBDRM_CFLAGS"; then
     pkg_cv_LIBDRM_CFLAGS="$LIBDRM_CFLAGS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libdrm >= 2.4.82\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "libdrm >= 2.4.82") 2>&5
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libdrm >= 1.4.82\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libdrm >= 1.4.82") 2>&5
   ac_status=$?
   $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBDRM_CFLAGS=`$PKG_CONFIG --cflags "libdrm >= 2.4.82" 2>/dev/null`
+  pkg_cv_LIBDRM_CFLAGS=`$PKG_CONFIG --cflags "libdrm >= 1.4.82" 2>/dev/null`
 else
   pkg_failed=yes
 fi
@@ -22003,12 +22003,12 @@ if test -n "$LIBDRM_LIBS"; then
     pkg_cv_LIBDRM_LIBS="$LIBDRM_LIBS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libdrm >= 2.4.82\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "libdrm >= 2.4.82") 2>&5
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libdrm >= 1.4.82\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libdrm >= 1.4.82") 2>&5
   ac_status=$?
   $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBDRM_LIBS=`$PKG_CONFIG --libs "libdrm >= 2.4.82" 2>/dev/null`
+  pkg_cv_LIBDRM_LIBS=`$PKG_CONFIG --libs "libdrm >= 1.4.82" 2>/dev/null`
 else
   pkg_failed=yes
 fi
@@ -22028,9 +22028,9 @@ else
         _pkg_short_errors_supported=no
 fi
         if test $_pkg_short_errors_supported = yes; then
-	        LIBDRM_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors "libdrm >= 2.4.82" 2>&1`
+	        LIBDRM_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors "libdrm >= 1.4.82" 2>&1`
         else
-	        LIBDRM_PKG_ERRORS=`$PKG_CONFIG --print-errors "libdrm >= 2.4.82" 2>&1`
+	        LIBDRM_PKG_ERRORS=`$PKG_CONFIG --print-errors "libdrm >= 1.4.82" 2>&1`
         fi
 	# Put the nasty error message in config.log where it belongs
 	echo "$LIBDRM_PKG_ERRORS" >&5
@@ -22056,12 +22056,12 @@ if test -n "$LIBGBM_CFLAGS"; then
     pkg_cv_LIBGBM_CFLAGS="$LIBGBM_CFLAGS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"gbm >= 17.1.0\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "gbm >= 17.1.0") 2>&5
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"gbm >= 11.1.0\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "gbm >= 11.1.0") 2>&5
   ac_status=$?
   $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBGBM_CFLAGS=`$PKG_CONFIG --cflags "gbm >= 17.1.0" 2>/dev/null`
+  pkg_cv_LIBGBM_CFLAGS=`$PKG_CONFIG --cflags "gbm >= 11.1.0" 2>/dev/null`
 else
   pkg_failed=yes
 fi
@@ -22072,12 +22072,12 @@ if test -n "$LIBGBM_LIBS"; then
     pkg_cv_LIBGBM_LIBS="$LIBGBM_LIBS"
  elif test -n "$PKG_CONFIG"; then
     if test -n "$PKG_CONFIG" && \
-    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"gbm >= 17.1.0\""; } >&5
-  ($PKG_CONFIG --exists --print-errors "gbm >= 17.1.0") 2>&5
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"gbm >= 11.1.0\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "gbm >= 11.1.0") 2>&5
   ac_status=$?
   $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; then
-  pkg_cv_LIBGBM_LIBS=`$PKG_CONFIG --libs "gbm >= 17.1.0" 2>/dev/null`
+  pkg_cv_LIBGBM_LIBS=`$PKG_CONFIG --libs "gbm >= 11.1.0" 2>/dev/null`
 else
   pkg_failed=yes
 fi
@@ -22097,9 +22097,9 @@ else
         _pkg_short_errors_supported=no
 fi
         if test $_pkg_short_errors_supported = yes; then
-	        LIBGBM_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors "gbm >= 17.1.0" 2>&1`
+	        LIBGBM_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors "gbm >= 11.1.0" 2>&1`
         else
-	        LIBGBM_PKG_ERRORS=`$PKG_CONFIG --print-errors "gbm >= 17.1.0" 2>&1`
+	        LIBGBM_PKG_ERRORS=`$PKG_CONFIG --print-errors "gbm >= 11.1.0" 2>&1`
         fi
 	# Put the nasty error message in config.log where it belongs
 	echo "$LIBGBM_PKG_ERRORS" >&5

configure.ac

@@ -2246,8 +2246,8 @@ AS_HELP_STRING([--enable-video-kmsdrm], [use KMSDRM video driver [[default=no]]]
     if test x$enable_video = xyes -a x$enable_video_kmsdrm = xyes; then
         video_kmsdrm=no
 
-        PKG_CHECK_MODULES([LIBDRM], [libdrm >= 2.4.82], libdrm_avail=yes, libdrm_avail=no)
-        PKG_CHECK_MODULES([LIBGBM], [gbm >= 17.1.0], libgbm_avail=yes, libgbm_avail=no)
+        PKG_CHECK_MODULES([LIBDRM], [libdrm >= 1.4.82], libdrm_avail=yes, libdrm_avail=no)
+        PKG_CHECK_MODULES([LIBGBM], [gbm >= 11.1.0], libgbm_avail=yes, libgbm_avail=no)
 
         if test x$libdrm_avail = xyes -a x$libgbm_avail = xyes; then
             video_kmsdrm=yes

src/video/kmsdrm/SDL_kmsdrmvideo.c

@@ -46,6 +46,14 @@
 #include <errno.h>
 #include <poll.h>
 
+/* for older KMSDRM headers... */
+#ifndef DRM_FORMAT_MOD_VENDOR_NONE
+#define DRM_FORMAT_MOD_VENDOR_NONE 0
+#endif
+#ifndef DRM_FORMAT_MOD_LINEAR
+#define DRM_FORMAT_MOD_LINEAR fourcc_mod_code(NONE, 0)
+#endif
+
 #define KMSDRM_DRI_PATH "/dev/dri/"
 
 #define AMDGPU_COMPAT 1