liblua: Use POSIX

Use the posix methods to avoid unsafe function warnings on FreeBSD.
Fixes the ports system warning about using tmpnam.

There is also USE_DLOPEN, but I'm not sure pkg needs to ever dlopen
something in its lua functions, so I'm leaving that one out.

Author: dankm

external/liblua/Makefile.autosetup

@@ -37,6 +37,6 @@ SRCS=	lapi.c \
 	loadlib.c \
 	linit.c
 
-LOCAL_CFLAGS=	-I$(top_srcdir)/external/lua/src
+LOCAL_CFLAGS=	-I$(top_srcdir)/external/lua/src -DLUA_USE_POSIX
 
 include $(MK)/static-lib.mk