Avoid -Wundef warnings for PNG_ARM_NEON_IMPLEMENTATION
Define this symbol as 0 instead of leaving it undefined when not using
ARM NEON optimizations.
No real changes, but just avoid a bunch of
"PNG_ARM_NEON_IMPLEMENTATION" is not defined, evaluates to 0 [-Wundef]
warnings when building the library.
diff --git a/pngpriv.h b/pngpriv.h
index 2fa614f..c07750c 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -185,6 +185,8 @@
/* Use the intrinsics code by default. */
# define PNG_ARM_NEON_IMPLEMENTATION 1
# endif
+#else /* PNG_ARM_NEON_OPT == 0 */
+# define PNG_ARM_NEON_IMPLEMENTATION 0
#endif /* PNG_ARM_NEON_OPT > 0 */
#ifndef PNG_MIPS_MSA_OPT
