tccpp: cleanup options -dD -dM, remove -C

The lexer is for reading files, not for writing.

Also :
- macro_is_equal(): avoid crash if redefining __FILE__

tcc.c

@@ -98,9 +98,8 @@ static void help(void)
            "  -Dsym[=val] define 'sym' with value 'val'\n"
            "  -Usym       undefine 'sym'\n"
            "  -E          preprocess only\n"
-           "    -P[1]       no/alternative output of #line directives\n"
-           "    -d{D|M}     dump defines\n"
-           "    -C          keep comments\n"
+           "  -P[1]       no / alternative #line output with -E\n"
+           "  -dD -dM     output #define directives with -E\n"
            "Linker options:\n"
            "  -Ldir       add library path 'dir'\n"
            "  -llib       link with dynamic or static library 'lib'\n"