Check libpng directly into third_party/

third_party/libpng/scripts/makefile.amiga

+# Commodore Amiga Makefile
+# makefile for libpng and SAS C V6.5x compiler
+# Copyright (C) 1995-2000 Wolf Faust
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+#
+# Location/path of zlib include files
+ZLIB=/zlib
+#compiler
+CC=sc
+#compiler flags
+# WARNING: a bug in V6.51 causes bad code with OPTGO
+#          So use V6.55 or set NOOPTGO!!!!!!!!!
+CFLAGS= NOSTKCHK PARMS=REG OPTIMIZE OPTGO OPTPEEP OPTINLOCAL OPTINL\
+        OPTLOOP OPTRDEP=4 OPTDEP=4 OPTCOMP=4 INCLUDEDIR=$(ZLIB) \
+        DEFINE=PNG_INTERNAL
+#linker flags
+LDFLAGS= SD ND BATCH
+#link libs
+LDLIBS= libpng.lib libgz.lib LIB:scm.lib LIB:sc.lib Lib:amiga.lib
+# linker
+LN= slink
+# file deletion command
+RM= delete quiet
+# library (.lib) file creation command
+AR= oml
+# make directory command
+MKDIR= makedir
+
+# Pre-built configuration
+# See scripts/pnglibconf.mak for more options
+PNGLIBCONF_H_PREBUILT = scripts/pnglibconf.h.prebuilt
+
+OBJS = png.o pngset.o pngget.o pngrutil.o pngtrans.o pngwutil.o \
+        pngread.o pngrio.o pngwio.o pngwrite.o pngrtran.o \
+        pngwtran.o pngmem.o pngerror.o pngpread.o
+
+all: libpng.lib pngtest
+
+libpng.lib: $(OBJS)
+-$(RM) libpng.lib
+$(AR) libpng.lib r $(OBJS)
+
+$(OBJS): pngpriv.h png.h pngconf.h pnglibconf.h pnginfo.h pngstruct.h pngdebug.h
+
+pnglibconf.h: $(PNGLIBCONF_H_PREBUILT)
+COPY $(PNGLIBCONF_H_PREBUILT) TO pnglibconf.h
+
+pngtest: pngtest.o libpng.lib
+$(LN) <WITH <
+$(LDFLAGS)
+TO pngtest
+FROM LIB:c.o pngtest.o
+LIB $(LDLIBS)
+<
+