CMake: `SKIP_COMPOSITING` -> `SKIP_UNITY_BUILD_INCLUSION`

The latter is what CMake (3.16+) itself uses; we should start using
CMake's own unity build capabilities if available.

cmake/macros/CompositeSources.cmake

@@ -49,7 +49,7 @@ function(composite_sources target sources_var)
     get_filename_component(extension "${source}" EXT)
     get_source_file_property(generated "${source}" GENERATED)
     get_source_file_property(is_header "${source}" HEADER_FILE_ONLY)
-    get_source_file_property(skip_compositing "${source}" SKIP_COMPOSITING)
+    get_source_file_property(skip_compositing "${source}" SKIP_UNITY_BUILD_INCLUSION)
 
     # Check if we can safely add this to a composite file.
     if(NOT generated AND NOT is_header AND NOT skip_compositing AND

dtool/src/dtoolbase/CMakeLists.txt

@@ -83,7 +83,7 @@ set(P3DTOOLBASE_IGATEEXT
   typeHandle_ext.h
 )
 
-set_source_files_properties(indent.cxx PROPERTIES SKIP_COMPOSITING YES)
+set_source_files_properties(indent.cxx PROPERTIES SKIP_UNITY_BUILD_INCLUSION YES)
 
 composite_sources(p3dtoolbase P3DTOOLBASE_SOURCES)
 add_component_library(p3dtoolbase NOINIT SYMBOL BUILDING_DTOOL_DTOOLBASE

dtool/src/dtoolutil/CMakeLists.txt

@@ -34,7 +34,7 @@ if(APPLE)
   set_source_files_properties(
     filename_assist.mm filename_assist.h PROPERTIES
     WRAP_EXCLUDE YES
-    SKIP_COMPOSITING YES)
+    SKIP_UNITY_BUILD_INCLUSION YES)
 endif()
 
 set(P3DTOOLUTIL_SOURCES

panda/src/display/CMakeLists.txt

@@ -91,7 +91,7 @@ if(APPLE)
 endif()
 
 # This is a large file; let's build it separately
-set_source_files_properties(graphicsStateGuardian.cxx PROPERTIES SKIP_COMPOSITING YES)
+set_source_files_properties(graphicsStateGuardian.cxx PROPERTIES SKIP_UNITY_BUILD_INCLUSION YES)
 
 composite_sources(p3display P3DISPLAY_SOURCES)
 add_component_library(p3display SYMBOL BUILDING_PANDA_DISPLAY

panda/src/dxgsg9/CMakeLists.txt

@@ -36,7 +36,7 @@ set(P3DXGSG9_SOURCES
 )
 
 # This is a large file; let's build it separately
-set_source_files_properties(dxGraphicsStateGuardian9.cxx PROPERTIES SKIP_COMPOSITING YES)
+set_source_files_properties(dxGraphicsStateGuardian9.cxx PROPERTIES SKIP_UNITY_BUILD_INCLUSION YES)
 
 composite_sources(p3dxgsg9 P3DXGSG9_SOURCES)
 add_component_library(p3dxgsg9 SYMBOL BUILDING_PANDADX

panda/src/grutil/CMakeLists.txt

@@ -39,7 +39,7 @@ set(P3GRUTIL_SOURCES
 )
 
 # This is a large file; let's build it separately
-set_source_files_properties(multitexReducer.cxx PROPERTIES SKIP_COMPOSITING YES)
+set_source_files_properties(multitexReducer.cxx PROPERTIES SKIP_UNITY_BUILD_INCLUSION YES)
 
 composite_sources(p3grutil P3GRUTIL_SOURCES)
 add_component_library(p3grutil SYMBOL BUILDING_PANDA_GRUTIL

panda/src/pgraph/CMakeLists.txt

@@ -222,7 +222,7 @@ set(P3PGRAPH_IGATEEXT
 )
 
 # This is a large file; let's build it separately
-set_source_files_properties(nodePath.cxx PROPERTIES SKIP_COMPOSITING YES)
+set_source_files_properties(nodePath.cxx PROPERTIES SKIP_UNITY_BUILD_INCLUSION YES)
 
 composite_sources(p3pgraph P3PGRAPH_SOURCES)
 add_component_library(p3pgraph SYMBOL BUILDING_PANDA_PGRAPH

panda/src/pnmimage/CMakeLists.txt

@@ -35,7 +35,7 @@ set(P3PNMIMAGE_IGATEEXT
 if(HAVE_SSE2 AND CMAKE_SIZEOF_VOID_P EQUAL 4 AND CMAKE_SYSTEM_PROCESSOR MATCHES "86")
   # It's only necessary to do this on 32-bit x86; 64-bit makes SSE2 builtin.
   set_source_files_properties(convert_srgb_sse2.cxx PROPERTIES
-    SKIP_COMPOSITING YES
+    SKIP_UNITY_BUILD_INCLUSION YES
     COMPILE_FLAGS -msse2)
 endif()