Silence sync.h warning we got when  compiling with clang `-Wthread-safety-analysis` on
Silence sync.h warning we got when  compiling with clang `-Wthread-safety-analysis` on

The warning is related to the code in `CDeferredSharedLocker` and this is the text:

../../src/sync.h:151:5: warning: mutex 'scs' is not held on every path through here [-Wthread-safety-analysis]
    }
    ^
../../src/sync.h:148:17: note: mutex acquired here
            scs.lock();
                ^
../../src/sync.h:158:17: warning: releasing mutex 'scs' that was not held [-Wthread-safety-analysis]
            scs.unlock();
                ^
This seems like a false positive to me but I defer to @gandrewstone
and @Greg-Griffith opinion on that. Pragma will be used only when the
code is compiled via clang.

Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited