[CMake] Minor fix to regex in r279152

The third version component is optional in Xcode's version spew, so we need to make it optional in the regex.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279153 91177308-0d34-0410-b5e6-96231b3b80d8

tools/xcode-toolchain/CMakeLists.txt

@@ -49,7 +49,7 @@ if(NOT XCODE_VERSION)
     OUTPUT_STRIP_TRAILING_WHITESPACE
     ERROR_FILE /dev/null
   )
-  string(REGEX MATCH "Xcode ([0-9][.][0-9][.][0-9])" version_match ${xcodebuild_version})
+  string(REGEX MATCH "Xcode ([0-9]([.][0-9])+)" version_match ${xcodebuild_version})
   if(version_match)
     message(STATUS "Identified Xcode Version: ${CMAKE_MATCH_1}")
     set(XCODE_VERSION ${CMAKE_MATCH_1})