cmd/ld: fix gdbscript

R=golang-dev, lvd
CC=golang-dev
https://golang.org/cl/5601058

src/cmd/ld/dwarf.c

diff --git a/src/cmd/ld/dwarf.c b/src/cmd/ld/dwarf.c
index d0ecabf..dfd8797 100644
--- a/src/cmd/ld/dwarf.c
+++ b/src/cmd/ld/dwarf.c
@@ -1601,7 +1601,7 @@
 	char *c;
 
 	for (i = 1; i < histfilesize; i++) {
-		if ((c = strstr(histfile[i], "runtime/runtime_defs.go")) != nil) {
+		if ((c = strstr(histfile[i], "runtime/zruntime_defs")) != nil) {
 			l = c - histfile[i];
 			memmove(gdbscript, histfile[i], l);
 			memmove(gdbscript + l, "runtime/runtime-gdb.py", strlen("runtime/runtime-gdb.py") + 1);