libtcc: Allow multiple options for -Wl separated with ','

I moved the code to libtcc to prepare for a later tiny_ld

--
By by ... Detlef

libtcc.h

@@ -31,6 +31,9 @@ LIBTCCAPI void tcc_set_error_func(TCCState *s, void *error_opaque,
 /* set/reset a warning */
 LIBTCCAPI int tcc_set_warning(TCCState *s, const char *warning_name, int value);
 
+/* set linker option */
+LIBTCCAPI const char * tcc_set_linker(TCCState *s, const char *option, int multi);
+
 /*****************************/
 /* preprocessor */