configure: pass CONFIG_xxxDIR/PATH options via commandline

- except for CONFIG_SYSROOT and CONFIG_TCCDIR

Strictly neccessary it is only for CONFIG_MULTIARCHDIR
because otherwise if it's in config.h it is impossible to
leave it undefined.

But it is also nicer not to use these definitions for
cross-compilers.

- Also:
lib/Makefile : include ../Makefile for CFLAGS
lib/libtcc1.c : fix an issue compiling tcc with tcc on x64

tcc.c

@@ -223,6 +223,7 @@ static void display_info(TCCState *s, int what)
         print_paths("crt", s->crt_paths, s->nb_crt_paths);
         print_paths("libraries", s->library_paths, s->nb_library_paths);
         print_paths("include", s->sysinclude_paths, s->nb_sysinclude_paths);
+        printf("elfinterp:\n  %s\n",  CONFIG_TCC_ELFINTERP);
         break;
     }
 }