A gcc preprocessor option -dD added

With this option on a defines are included into the output
(inside comments). This will allow to debug a problems like:

    In file included from math.c:8:
    In file included from /usr/include/math.h:43:
    /usr/include/bits/nan.h:52: warning: NAN redefined

1 files changed, 2 insertions, 0 deletions

diff --git a/tcc.h b/tcc.h
index f268aed..34d3248 100644
--- a/tcc.h
+++ b/tcc.h
@@ -661,6 +661,7 @@ struct TCCState {
 	LINE_MACRO_OUTPUT_FORMAT_NONE,
 	LINE_MACRO_OUTPUT_FORMAT_STD,
     }    Pflag; 
+    int  dflag; /* for keeping a -dD value */
 
     /* for -MD/-MF: collected dependencies for this compilation */
     char **target_deps;
@@ -1155,6 +1156,7 @@ ST_INLN void define_push(int v, int macro_type, int *str, Sym *first_arg);
 ST_FUNC void define_undef(Sym *s);
 ST_INLN Sym *define_find(int v);
 ST_FUNC void free_defines(Sym *b);
+void print_defines(void);
 ST_FUNC Sym *label_find(int v);
 ST_FUNC Sym *label_push(Sym **ptop, int v, int flags);
 ST_FUNC void label_pop(Sym **ptop, Sym *slast);