Fix compile error on s390x in shims/lock.h#235

MadCoder merged 1 commit intoswiftlang:swift-3.1-branchswiftlang/swift-corelibs-libdispatch:swift-3.1-branchfrom

linux-on-ibm-z:fix_compiler_error_swift31linux-on-ibm-z/swift-corelibs-libdispatch:fix_compiler_error_swift31Copy head branch name to clipboard