CMake: replace "CVS" with "Git"

dtool/PandaVersion.cmake

@@ -1,13 +1,14 @@
+
 # This file defines the current version number for Panda. It is read
 # by the top CMakeLists.txt, which puts it in the global namespace for
 # all CMake scripts for Panda.
 
 option(PANDA_OFFICIAL_VERSION
-  "This variable will be defined to false in the CVS repository, but
+  "This variable will be defined to false in the Git repository, but
 scripts that generate source tarballs and/or binary releases for
-distribution, by checking out Panda from an official CVS tag,
+distribution, by checking out Panda from an official Git tag,
 should explictly set this to true.  When false, it indicates that
-the current version of Panda was checked out from CVS, so it may
+the current version of Panda was checked out from Git, so it may
 not be a complete representation of the indicated version."
   OFF)
 

dtool/src/dtoolbase/pandaVersion.h.in

@@ -46,7 +46,7 @@
 
 /* This is the panda version expressed as a string.  It ends in the
    letter "c" if this is not an "official" version (e.g. it was checked
-   out from CVS by the builder). */
+   out from Git by the builder). */
 #define PANDA_VERSION_STR "@PANDA_VERSION_STR@"
 
 /* This is the build date expressed as a string.  It can be left undefined
@@ -56,7 +56,7 @@
 
 /* This is the Git commit we built Panda from, or an empty string if this isn't
    known. */
-#define PANDA_GIT_COMMIT_STR "@PANDA_GIT_COMMIT_STR@"
+#cmakedefine PANDA_GIT_COMMIT_STR "@PANDA_GIT_COMMIT_STR@"
 
 /* This is the version of the Panda3D ABI expressed as a string.
    This usually means the major and minor version. It should be the