move lua-5.4 -> external/luasrc

we have to use the name "luasrc" rather than just "lua" because lua
is in gitignore

external/luasrc/lprefix.h

@@ -0,0 +1,45 @@
+/*
+** $Id: lprefix.h $
+** Definitions for Lua code that must come before any other header file
+** See Copyright Notice in lua.h
+*/
+
+#ifndef lprefix_h
+#define lprefix_h
+
+
+/*
+** Allows POSIX/XSI stuff
+*/
+#if !defined(LUA_USE_C89)	/* { */
+
+#if !defined(_XOPEN_SOURCE)
+#define _XOPEN_SOURCE           600
+#elif _XOPEN_SOURCE == 0
+#undef _XOPEN_SOURCE  /* use -D_XOPEN_SOURCE=0 to undefine it */
+#endif
+
+/*
+** Allows manipulation of large files in gcc and some other compilers
+*/
+#if !defined(LUA_32BITS) && !defined(_FILE_OFFSET_BITS)
+#define _LARGEFILE_SOURCE       1
+#define _FILE_OFFSET_BITS       64
+#endif
+
+#endif				/* } */
+
+
+/*
+** Windows stuff
+*/
+#if defined(_WIN32)	/* { */
+
+#if !defined(_CRT_SECURE_NO_WARNINGS)
+#define _CRT_SECURE_NO_WARNINGS  /* avoid warnings about ISO C functions */
+#endif
+
+#endif			/* } */
+
+#endif
+