Allow skipping image builds when the binaries are already created

Makes it slightly easier to build images on Mac, will update in the
future with a cleaner construct.

Author: smarterclayton

Diff for: hack/build-images.sh

@@ -15,17 +15,19 @@ if [[ "${OS_RELEASE:-}" == "n" ]]; then
 	imagedir="${OS_OUTPUT_BINPATH}/linux/amd64"
 	# identical to build-cross.sh
 	os::build::os_version_vars
-	OS_RELEASE_COMMIT="${OS_GIT_VERSION//+/-}"
-	platform="$(os::build::host_platform)"
-	OS_BUILD_PLATFORMS=("${OS_IMAGE_COMPILE_PLATFORMS[@]:-${platform}}")
-	OS_IMAGE_COMPILE_TARGETS=("${OS_IMAGE_COMPILE_TARGETS[@]:-${OS_IMAGE_COMPILE_TARGETS_LINUX[@]}}")
-	OS_SCRATCH_IMAGE_COMPILE_TARGETS=("${OS_SCRATCH_IMAGE_COMPILE_TARGETS[@]:-${OS_SCRATCH_IMAGE_COMPILE_TARGETS_LINUX[@]}}")
-
-	echo "Building images from source ${OS_RELEASE_COMMIT}:"
-	echo
-	os::build::build_static_binaries "${OS_IMAGE_COMPILE_TARGETS[@]-}" "${OS_SCRATCH_IMAGE_COMPILE_TARGETS[@]-}"
-	os::build::place_bins "${OS_IMAGE_COMPILE_BINARIES[@]}"
-	echo
+	if [[ -z "${OS_RELEASE_LOCAL}" ]]; then
+		OS_RELEASE_COMMIT="${OS_GIT_VERSION//+/-}"
+		platform="$(os::build::host_platform)"
+		OS_BUILD_PLATFORMS=("${OS_IMAGE_COMPILE_PLATFORMS[@]:-${platform}}")
+		OS_IMAGE_COMPILE_TARGETS=("${OS_IMAGE_COMPILE_TARGETS[@]:-${OS_IMAGE_COMPILE_TARGETS_LINUX[@]}}")
+		OS_SCRATCH_IMAGE_COMPILE_TARGETS=("${OS_SCRATCH_IMAGE_COMPILE_TARGETS[@]:-${OS_SCRATCH_IMAGE_COMPILE_TARGETS_LINUX[@]}}")
+
+		echo "Building images from source ${OS_RELEASE_COMMIT}:"
+		echo
+		os::build::build_static_binaries "${OS_IMAGE_COMPILE_TARGETS[@]-}" "${OS_SCRATCH_IMAGE_COMPILE_TARGETS[@]-}"
+		os::build::place_bins "${OS_IMAGE_COMPILE_BINARIES[@]}"
+		echo
+	fi
 else
 	# Get the latest Linux release
 	if [[ ! -d _output/local/releases ]]; then