tccpp: alternative #pragma push/pop_macro

using next_nomacro() so that for example
    #define push_macro foobar
does not affect how the pragma works (same behavior
as gcc, albeit not MS's cl).

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")
      DEF(TOK_once, "once")
 
 /* builtin functions or variables */