Enable "netgo" library when we build a static binary with gccgo

Signed-off-by: Tatsushi Inagaki <e29253@jp.ibm.com>

hack/make/.dockerinit-gccgo

@@ -12,6 +12,7 @@ go build --compiler=gccgo \
 		-g
 		-Wl,--no-export-dynamic
 		$EXTLDFLAGS_STATIC_DOCKER
+		-lnetgo
 	" \
 	./dockerinit
 

hack/make/gccgo

@@ -8,6 +8,9 @@ BINARY_FULLNAME="$BINARY_NAME$BINARY_EXTENSION"
 
 source "$(dirname "$BASH_SOURCE")/.go-autogen"
 
+if [[ "${BUILDFLAGS[@]}" =~ 'netgo ' ]]; then
+	EXTLDFLAGS_STATIC_DOCKER+=' -lnetgo'
+fi
 go build -compiler=gccgo \
 	-o "$DEST/$BINARY_FULLNAME" \
 	"${BUILDFLAGS[@]}" \