[libpng16] $(CP) is now used alongside $(RM_F).  Also, use 'copy' instead

of 'cp' where applicable, and applied other minor makefile changes.
diff --git a/scripts/makefile.bor b/scripts/makefile.bor
index a032510..70236d6 100644
--- a/scripts/makefile.bor
+++ b/scripts/makefile.bor
@@ -12,10 +12,11 @@
 ## Where zlib.h, zconf.h and zlib_MODEL.lib are
 ZLIB_DIR=..\zlib
 
-## Compiler, linker and lib stuff
+## Compiler, linker, librarian and other tools
 CC=bcc
 LD=bcc
 LIB=tlib
+CP=copy
 
 !ifndef MODEL
 MODEL=l
@@ -112,7 +113,7 @@
 
 # try !inlude scripts\pnglibconf.mak for more options
 pnglibconf.h: scripts\pnglibconf.h.prebuilt
-	copy scripts\pnglibconf.h.prebuilt $@
+	$(CP) $< $@
 
 libpng: $(LIBNAME)