[libpng16] Allow an easy replacement of the default pre-built configuration
header with a custom header, via the make PNGLIBCONF_H_PREBUILT
macro.
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index 85ae6e8..48c3452 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -37,8 +37,7 @@
.c.o:
$(CC) -c $(CPPFLAGS) $(CFLAGS) -o $@ $<
-# see scripts/pnglibconf.mak for more options
-pnglibconf.h: scripts/pnglibconf.h.prebuilt
+pnglibconf.h: $(PNGLIBCONF_H_PREBUILT)
cp $< $@
pngtest.o: pngtest.c