Use `-analyzer-disable-all-checks` for disabling static analysis.

`-analyzer-disable-checker` without arguments causes an error in the
static analyzer, but due to a bug in Xcode < 6.0 it was silently
ignored. As of Xcode 6.1 `-analyzer-disable-all-checks` can be used
to disable static analysis for specfic files.

rdar://18907351
https://github.com/CocoaPods/CocoaPods/issues/2402