8313576: GCC 7 reports compiler warning in bundled freetype 2.13.0

Reviewed-by: shade, prr

make/modules/java.desktop/lib/Awt2dLibraries.gmk

@@ -448,6 +448,7 @@ else
     LIBFREETYPE_LIBS := -lfreetype
   endif
 
+  # gcc_ftobjs.c := maybe-uninitialized required for GCC 7 builds.
   $(eval $(call SetupJdkLibrary, BUILD_LIBFREETYPE, \
       NAME := freetype, \
       OPTIMIZATION := HIGHEST, \
@@ -456,6 +457,7 @@ else
       EXTRA_HEADER_DIRS := $(BUILD_LIBFREETYPE_HEADER_DIRS), \
       DISABLED_WARNINGS_microsoft := 4267 4244 4996, \
       DISABLED_WARNINGS_gcc := dangling-pointer stringop-overflow, \
+      DISABLED_WARNINGS_gcc_ftobjs.c := maybe-uninitialized, \
       LDFLAGS := $(LDFLAGS_JDKLIB) \
           $(call SET_SHARED_LIBRARY_ORIGIN), \
   ))