make mce-test a submodule

cloning mce-test from

    git://github.com/andikleen/mce-test.git

and use it as a submodule of git.

Signed-off-by: Caspar Zhang <caspar@casparzhang.com>
Reviewed-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Reviewed-by: Andi Kleen <andi.kleen@intel.com>
Acked-by: Shubham Goyal <shubham@linux.vnet.ibm.com>
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..e9eefdb
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "testcases/kernel/mce-test"]
+	path = testcases/kernel/mce-test
+	url = git://github.com/andikleen/mce-test.git