add -fno-PIC when using external linker on alpine

The Alpine toolchain enables PIE by default. Since the go linker does
not (yet) support PIE we need to explicitly disable it on Alpine.

This is a workaround for golang/go#14851

Author: ncopa

1.6/alpine/Dockerfile

@@ -8,6 +8,9 @@ ENV GOLANG_BOOTSTRAP_VERSION 1.4.3
 ENV GOLANG_BOOTSTRAP_URL https://golang.org/dl/go$GOLANG_BOOTSTRAP_VERSION.src.tar.gz
 ENV GOLANG_BOOTSTRAP_SHA1 486db10dc571a55c8d795365070f66d343458c48
 
+# https://golang.org/issue/14851
+COPY no-pic.patch /
+
 RUN set -ex \
 	&& apk add --no-cache --virtual .build-deps \
 		bash \
@@ -30,9 +33,10 @@ RUN set -ex \
 	&& tar -C /usr/local -xzf golang.tar.gz \
 	&& rm golang.tar.gz \
 	&& cd /usr/local/go/src \
+	&& patch -p2 -i /no-pic.patch \
 	&& ./make.bash \
 	\
-	&& rm -rf /usr/local/bootstrap /usr/local/go/pkg/bootstrap \
+	&& rm -rf /usr/local/bootstrap /usr/local/go/pkg/bootstrap /*.patch \
 	&& apk del .build-deps
 
 ENV GOPATH /go

1.6/alpine/no-pic.patch

@@ -0,0 +1,16 @@
+diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
+index 8ccbec9dd634..4e96bfadc260 100644
+--- a/src/cmd/link/internal/ld/lib.go
++++ b/src/cmd/link/internal/ld/lib.go
+@@ -1194,6 +1194,11 @@ func hostlink() {
+ 		argv = append(argv, peimporteddlls()...)
+ 	}
+ 
++	// The Go linker does not currently support building PIE
++	// executables when using the external linker. See:
++	// https://github.com/golang/go/issues/6940
++	argv = append(argv, "-fno-PIC")
++
+ 	if Debug['v'] != 0 {
+ 		fmt.Fprintf(&Bso, "host link:")
+ 		for _, v := range argv {