Move submodules to where they belong. (#240)

diff --git a/.gitmodules b/.gitmodules
index e646b7d..0e03f4e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,6 @@
 [submodule "googletest"]
-	path = googletest
+	path = third_party/googletest
 	url = https://github.com/google/googletest
 [submodule "cpuinfo"]
-	path = cpuinfo
+	path = third_party/cpuinfo
 	url = https://github.com/pytorch/cpuinfo
diff --git a/cpuinfo b/third_party/cpuinfo
similarity index 100%
rename from cpuinfo
rename to third_party/cpuinfo
diff --git a/googletest b/third_party/googletest
similarity index 100%
rename from googletest
rename to third_party/googletest