8209115: adjust libsplashscreen linux ppc64le builds for easier libpng update

Reviewed-by: prr, dholmes

make/lib/Awt2dLibraries.gmk

@@ -796,6 +796,12 @@ ifeq ($(ENABLE_HEADLESS_ONLY), false)
 
   LIBSPLASHSCREEN_CFLAGS += -DSPLASHSCREEN -DPNG_NO_MMX_CODE -DPNG_ARM_NEON_OPT=0
 
+  ifeq ($(OPENJDK_TARGET_OS), linux)
+    ifeq ($(OPENJDK_TARGET_CPU_ARCH), ppc)
+      LIBSPLASHSCREEN_CFLAGS += -DPNG_POWERPC_VSX_OPT=0
+    endif
+  endif
+
   ifeq ($(OPENJDK_TARGET_OS), macosx)
     LIBSPLASHSCREEN_CFLAGS += -DWITH_MACOSX
 

src/java.desktop/share/native/libsplashscreen/libpng/pngpriv.h

@@ -290,13 +290,10 @@
 #  endif
 #endif /* PNG_MIPS_MSA_OPT > 0 */
 
-#ifdef PNG_POWERPC_VSX_API_SUPPORTED
 #if PNG_POWERPC_VSX_OPT > 0
 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
 #  define PNG_POWERPC_VSX_IMPLEMENTATION 1
 #endif
-#endif
-
 
 /* Is this a build of a DLL where compilation of the object modules requires
  * different preprocessor settings to those required for a simple library?  If