runtime: update type descriptor name in fieldtrack C support code

We were using the old name, but nothing noticed because it is a weak
reference that is permitted to be nil, so that it works with code that
does not use the field tracking library.

Change-Id: I0650b96ca3e9f192338920f29d848aff49472e7f
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/275449
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/libgo/runtime/go-fieldtrack.c b/libgo/runtime/go-fieldtrack.c
index 22f091b..80be27c 100644
--- a/libgo/runtime/go-fieldtrack.c
+++ b/libgo/runtime/go-fieldtrack.c
@@ -31,7 +31,7 @@
 // The type descriptor for map[string] bool.  */
 extern const char map_string_bool[] __attribute__ ((weak));
 extern const char map_string_bool[]
-  __asm__ (GOSYM_PREFIX "type..map.6string.7bool");
+  __asm__ (GOSYM_PREFIX "type..map_6string_7bool");
 
 void runtime_Fieldtrack (void *) __asm__ (GOSYM_PREFIX "runtime.Fieldtrack");