Merge pull request #1697 from morris-stock/ignore-cmake-generated-files

Ignore cmake generated files when used as submodule
diff --git a/.gitignore b/.gitignore
index 16c56e6..73cdd2c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,3 +41,14 @@
 
 # macOS files
 .DS_Store
+
+# Ignore cmake generated directories and files.
+CMakeFiles
+CTestTestfile.cmake
+Makefile
+cmake_install.cmake
+googlemock/CMakeFiles
+googlemock/CTestTestfile.cmake
+googlemock/Makefile
+googlemock/cmake_install.cmake
+googlemock/gtest