Support linker options passed in several -Wl param

ld support arguments to multiple-letter options being passed in two
ways:
* -opt=arg
* -opt arg

libtool generate command line of the second form. This commit add
support for the second form so that libtool works with tcc. The way it
is done is to concatenate all -Wl options into one and then pass it to
set_linker.

libtcc.c

@@ -1566,6 +1566,9 @@ PUB_FUNC const char * tcc_set_linker(TCCState *s, char *option, int multi)
             s->text_addr = strtoull(p, &end, 16);
             s->has_text_addr = 1;
         } else {
+            char *comma_ptr = strchr(option, ',');
+            if (comma_ptr)
+                *comma_ptr = '\0';
             return option;
         }