Make CTest.UpdateGIT robust to Git safecrlf on Windows

If the user has configured 'core.autocrlf' and 'core.safecrlf' then
'git submodule add' will fail to 'git add' the '.gitmodules' file because
it has LF newlines, at least as of Git 1.7.11.  Disable 'core.safecrlf'
in our test repository to avoid the problem.

Tests/CTestUpdateGIT.cmake.in

@@ -90,6 +90,9 @@ ${AUTHOR_CONFIG}")
 run_child(WORKING_DIRECTORY ${TOP}/import
   COMMAND ${GIT} add .
   )
+run_child(WORKING_DIRECTORY ${TOP}/import
+  COMMAND ${GIT} config core.safecrlf false
+  )
 run_child(WORKING_DIRECTORY ${TOP}/import
   COMMAND ${GIT} submodule add ${MOD_REPO} module
   )