Turn off uninitialized warnings for GCC up to 14.

Although the false positives that caused it to be disabled originally
may have been fixed in GCC 12, GCC also suffers from a problem where
-Wuninitialized may cause the build to hang on some platforms
(GCC llvm#120729). This has been fixed in GCC 15, so turn on -Wuninitialized
for GCC 15+ instead of GCC 12+.

Author: hvdijk

llvm/cmake/config-ix.cmake

@@ -510,7 +510,7 @@ set(USE_NO_UNINITIALIZED 0)
 # false positives.
 if (CMAKE_COMPILER_IS_GNUCXX)
   # Disable all -Wuninitialized warning for old GCC versions.
-  if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 12.0)
+  if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 15.0)
     set(USE_NO_UNINITIALIZED 1)
   else()
     set(USE_NO_MAYBE_UNINITIALIZED 1)