* and #pragma pop_macro("macro_name")

* give warning if pragma is unknown for tcc
    * don't free asm_label in sym_free(),
      it's a job of the asm_free_labels().

    The above pragmas are used in the mingw headers.
    Thise pragmas are implemented in gcc-4.5+ and current
    clang.

tcctok.h

@@ -155,6 +155,8 @@
 #endif
      DEF(TOK_comment, "comment")
      DEF(TOK_lib, "lib")
+     DEF(TOK_push_macro, "push_macro")
+     DEF(TOK_pop_macro, "pop_macro")
 
 /* builtin functions or variables */
 #ifndef TCC_ARM_EABI