buildman: Add gcc 4.9.0 with Microblaze toolchain

Also read gcc 4.9.0 at kernel.org which also have Microblaze toolchain.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

Fixed unit test failure by updating the test:
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/test.py b/tools/buildman/test.py
index 7642d94..d8f3c81 100644
--- a/tools/buildman/test.py
+++ b/tools/buildman/test.py
@@ -411,7 +411,7 @@
 
     def testToolchainDownload(self):
         """Test that we can download toolchains"""
-        self.assertEqual('https://www.kernel.org/pub/tools/crosstool/files/bin/x86_64/4.6.3/x86_64-gcc-4.6.3-nolibc_arm-unknown-linux-gnueabi.tar.xz',
+        self.assertEqual('https://www.kernel.org/pub/tools/crosstool/files/bin/x86_64/4.9.0/x86_64-gcc-4.9.0-nolibc_arm-unknown-linux-gnueabi.tar.xz',
             self.toolchains.LocateArchUrl('arm'))