CircleCI: Use XCode 8.2 to make brew happy

sschuberth · sschuberth · commit e3ea18be6819 · 2017-02-24T16:03:13.000+01:00
This should solve build errors like the one in https://circleci.com/gh/git-lfs/git-lfs/1012
diff --git a/circle.yml b/circle.yml
@@ -10,6 +10,8 @@ machine:
     GOPATH: $HOME/git-lfs/.go
     NO_OPENSSL: YesPlease
     APPLE_COMMON_CRYPTO: YesPlease
+  xcode:
+    version: 8.2
 
 general:
   build_dir: .go/src/github.com/git-lfs/git-lfs
