libtcc: cleanup @listfile

Also:
- allow more than one item per line
- respect "quoted items" and escaped quotes \"
  (also for LIBTCCAPI tcc_setoptions)

- cleanup some copy & paste

tccpp.c

@@ -133,21 +133,6 @@ ST_FUNC void end_macro(void)
     }
 }
 
-ST_FUNC char *trimfront(char *p)
-{
-    while (*p && (unsigned char)*p <= ' ')
-	++p;
-    return p;
-}
-
-ST_FUNC char *trimback(char *a, char *e)
-{
-    while (e > a && (unsigned char)e[-1] <= ' ')
-	--e;
-    *e = 0;;
-    return a;
-}
-
 /* ------------------------------------------------------------------------- */
 /* Custom allocator for tiny objects */