make.bash: do not overwrite GO_LDSO if already set

Change-Id: I704bdb411bda3d8a40906c12f182e268dca4718f
Reviewed-on: https://go-review.googlesource.com/c/go/+/340450
Trust: Cherry Mui <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: cherrymui

src/make.bash

@@ -130,8 +130,8 @@ if [ "$(uname -s)" = "GNU/kFreeBSD" ]; then
 	export CGO_ENABLED=0
 fi
 
-# Test which linker/loader our system is using
-if type readelf >/dev/null 2>&1; then
+# Test which linker/loader our system is using, if GO_LDSO is not set.
+if [ -z "$GO_LDSO" ] && type readelf >/dev/null 2>&1; then
 	if echo "int main() { return 0; }" | ${CC:-cc} -o ./test-musl-ldso -x c - >/dev/null 2>&1; then
 		LDSO=$(readelf -l ./test-musl-ldso | grep 'interpreter:' | sed -e 's/^.*interpreter: \(.*\)[]]/\1/') >/dev/null 2>&1
 		[ -z "$LDSO" ] || export GO_LDSO="$LDSO"