Bring git-hooks in as a submodule

git-hooks tracks git hook scripts for SwiftShader. Using git config we
can tell git to use these scripts instead of what's in .git/hooks.

Bug: b/187094215
Change-Id: I2df090c47ceeb1b352960576a34f259b75946302
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/54528
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Sean Risser <srisser@google.com>
Commit-Queue: Sean Risser <srisser@google.com>
diff --git a/.gitmodules b/.gitmodules
index 1b368e5..1526a1c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -22,3 +22,6 @@
 [submodule "third_party/angle/angle"]
 	path = third_party/angle/angle
 	url = https://chromium.googlesource.com/angle/angle
+[submodule "third_party/git-hooks"]
+	path = third_party/git-hooks
+	url = https://swiftshader.googlesource.com/git-hooks
diff --git a/third_party/git-hooks b/third_party/git-hooks
new file mode 160000
index 0000000..ab624f6
--- /dev/null
+++ b/third_party/git-hooks
@@ -0,0 +1 @@
+Subproject commit ab624f65cb6ce94738a5ea9d4cc51d5097bc34e7