Lua: Upgrade cjson to 2.1.0 (2012-03-01)

The new cjson has some improvements over our current version including
increased platform compatability, a new resource limit to restrict
decode depth, and better invalid number handling.

One minor change was required to deps/Makefile because this version
of cjson doesn't export itself globally, so we added a quick little
define of -DENABLE_CJSON_GLOBAL.

cjson now has an optional higher performing float parsing interface,
but we are not including it (g_fmt.c, dtoa.c) because it requires
endianness declaration during compile time.

This commit is exactly lua_cjson.c from 2.1.0 with one minor
change of altering the two Lua includes for local search
instead of system-wide importing.

deps/lua/src/fpconv.h

@@ -0,0 +1,22 @@
+/* Lua CJSON floating point conversion routines */
+
+/* Buffer required to store the largest string representation of a double.
+ *
+ * Longest double printed with %.14g is 21 characters long:
+ * -1.7976931348623e+308 */
+# define FPCONV_G_FMT_BUFSIZE   32
+
+#ifdef USE_INTERNAL_FPCONV
+static inline void fpconv_init()
+{
+    /* Do nothing - not required */
+}
+#else
+extern inline void fpconv_init();
+#endif
+
+extern int fpconv_g_fmt(char*, double, int);
+extern double fpconv_strtod(const char*, char**);
+
+/* vi:ai et sw=4 ts=4:
+ */