Detect Git repositories for CTest UPDATE_TYPE

The CTest module configures the command-line CTest dashboard mode.
We teach it to recognize .git directories.

Modules/CTest.cmake

@@ -126,6 +126,7 @@ IF(BUILD_TESTING)
   FIND_PROGRAM(SVNCOMMAND svn)
   FIND_PROGRAM(BZRCOMMAND bzr)
   FIND_PROGRAM(HGCOMMAND hg)
+  FIND_PROGRAM(GITCOMMAND git)
 
   IF(NOT UPDATE_TYPE)
     IF(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/CVS")
@@ -136,6 +137,8 @@ IF(BUILD_TESTING)
       SET(UPDATE_TYPE bzr)
     ELSEIF(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.hg")
       SET(UPDATE_TYPE hg)
+    ELSEIF(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git")
+      SET(UPDATE_TYPE git)
     ENDIF()
   ENDIF(NOT UPDATE_TYPE)
 
@@ -159,6 +162,9 @@ IF(BUILD_TESTING)
   ELSEIF("${_update_type}" STREQUAL "hg")
     SET(UPDATE_COMMAND "${HGCOMMAND}")
     SET(UPDATE_OPTIONS "${HG_UPDATE_OPTIONS}")
+  ELSEIF("${_update_type}" STREQUAL "git")
+    SET(UPDATE_COMMAND "${GITCOMMAND}")
+    SET(UPDATE_OPTIONS "${GIT_UPDATE_OPTIONS}")
   ENDIF()
 
   SET(DART_TESTING_TIMEOUT 1500 CACHE STRING 
@@ -252,6 +258,7 @@ IF(BUILD_TESTING)
     SVNCOMMAND
     BZRCOMMAND
     HGCOMMAND
+    GITCOMMAND
     CVS_UPDATE_OPTIONS
     SVN_UPDATE_OPTIONS
     BZR_UPDATE_OPTIONS