Add googletest submodule

Signed-off-by: Tomasz Michalak <tmichalak@antmicro.com>

.gitmodules

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..8d4f8c9
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "third_party/googletest"]
+	path = third_party/googletest
+	url = https://github.com/google/googletest

third_party/googletest

diff --git a/third_party/googletest b/third_party/googletest
new file mode 160000
index 0000000..41b5f14
--- /dev/null
+++ b/third_party/googletest
@@ -0,0 +1 @@
+Subproject commit 41b5f149ab306e96b5b2faf523505d75acffd98a