cmd/dist, cmd/ld: GO_EXTLINK_ENABLED=0 defaults to -linkmode=internal

Change build system to set GO_EXTLINK_ENABLED=0 by default for
OS X 10.6, since the system linker has a bug and can not
handle the object files generated by 6l.

Fixes issue 5130.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/8183043

1 files changed, 6 insertions, 0 deletions

diff --git a/src/lib9/goos.c b/src/lib9/goos.c
index 3b0027111..2d4a800dd 100644
--- a/src/lib9/goos.c
+++ b/src/lib9/goos.c
@@ -51,3 +51,9 @@ getgo386(void)
 {
 	return defgetenv("GO386", GO386);
 }
+
+char *
+getgoextlinkenabled(void)
+{
+	return GO_EXTLINK_ENABLED;
+}