[scan-build] Accept -fno-objc-arc as well as -fobjc-arc.

This is how Xcode lets individual files be marked as non-ARC when the rest
of the project is ARC-enabled, so this is necessary for scan-build xcodebuild.

Patch by Paul Eipper!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162497 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed