[libpng16] Only compile ARM code when PNG_READ_SUPPORTED is defined.
diff --git a/arm/arm_init.c b/arm/arm_init.c
index 36eacde..33d6672 100644
--- a/arm/arm_init.c
+++ b/arm/arm_init.c
@@ -16,6 +16,7 @@
 
 #include "../pngpriv.h"
 
+#ifdef PNG_READ_SUPPORTED
 #if PNG_ARM_NEON_OPT > 0
 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
 #include <signal.h> /* for sig_atomic_t */
@@ -217,3 +218,4 @@
    }
 }
 #endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* PNG_READ_SUPPORTED */