Make gcc mandatory on OSX, since clang lacks certain GAS features

Makefile

@@ -1,6 +1,7 @@
 #GOPATH := $(CURDIR)/tmp/gopath
 MAKE_OPTIONS := -s
 ARCH := $(shell uname -s)
+GCCVERSIONGTEQ4 := $(shell expr `gcc -dumpversion | cut -f1 -d.` \>= 4)
 
 all: getdeps install
 
@@ -19,7 +20,11 @@ build-utils:
 	@godep go test -race -coverprofile=cover.out github.com/minio-io/minio/pkg/utils/crypto/sha1
 	@godep go test -race -coverprofile=cover.out github.com/minio-io/minio/pkg/utils/crypto/sha256
 	@godep go test -race -coverprofile=cover.out github.com/minio-io/minio/pkg/utils/crypto/sha512
-ifeq ($(ARCH), Linux)
+ifeq ($(ARCH), Darwin)
+ifeq ($(GCCVERSIONGTEQ4), "1")
+	@godep go test -race -coverprofile=cover.out github.com/minio-io/minio/pkg/utils/checksum/crc32c
+endif
+else
 	@godep go test -race -coverprofile=cover.out github.com/minio-io/minio/pkg/utils/checksum/crc32c
 endif
 

checkdeps.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 echo -n "Checking if proper environment variables are set.. "
 

pkg/utils/checksum/crc32c/crc32c_amd64.S

@@ -454,22 +454,18 @@ full_block:
 crc_array:
 	i=128
 .rept 128-1
-#if !defined(__clang__)
 .altmacro
 LABEL crc_ %i
 .noaltmacro
-#endif
 	crc32q   -i*8(block_0), crc_init
 	crc32q   -i*8(block_1), crc1
 	crc32q   -i*8(block_2), crc2
 	i=(i-1)
 .endr
 
-#if !defined(__clang__)
 .altmacro
 LABEL crc_ %i
 .noaltmacro
-#endif
 	crc32q   -i*8(block_0), crc_init
 	crc32q   -i*8(block_1), crc1
 # SKIP  crc32  -i*8(block_2), crc2 ; Don't do this one yet