py/gc: Make gc_dump_info/gc_dump_alloc_table take a printer as argument.

So that callers can redirect the output if needed.

Signed-off-by: Damien George <damien@micropython.org>

ports/powerpc/main.c

@@ -108,7 +108,7 @@ void gc_collect(void) {
     gc_collect_start();
     gc_collect_root(&dummy, ((mp_uint_t)stack_top - (mp_uint_t)&dummy) / sizeof(mp_uint_t));
     gc_collect_end();
-    gc_dump_info();
+    gc_dump_info(&mp_plat_print);
 }
 
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {