cmake: silence repeated git searches too

Author: vuvova

cmake/FindGit.cmake

@@ -0,0 +1,13 @@
+if(GIT_EXECUTABLE)
+  set(GIT_FOUND TRUE)
+  return()
+endif()
+if(DEFINED GIT_EXECUTABLE)
+  set(GIT_FOUND FALSE)
+  return()
+endif()
+
+set(orig_CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH})
+unset(CMAKE_MODULE_PATH)
+include(FindGit)
+set(CMAKE_MODULE_PATH ${orig_CMAKE_MODULE_PATH})