Fix compile error on s390x in shims/lock.h#234

MadCoder merged 1 commit intoswiftlang:masterswiftlang/swift-corelibs-libdispatch:masterfrom

linux-on-ibm-z:fix_compile_errorlinux-on-ibm-z/swift-corelibs-libdispatch:fix_compile_errorCopy head branch name to clipboard