Unit Tests failing on Alpine Linux due to non-portable mutex initializers

It seems that the lib/cpp/test suite is broken in the 0.11.0 tagged release because this fails in Ubuntu Bionic and inside of an Alpine Linux 3.8 Docker container.

I would have thought all test suites would pass for tagged releases.

In any case, I've narrowed the culprits down to the non-portable (NP) class of Mutex initializers.

I'd rather not speculate at this point exactly why this problem is happening. Currently my patching just disables those tests undonditionally, but there should probably be a better solution used in the end. E.g. better .m4 testing for non-portable pthread features - if they are actually functional or just stubs.

Currently, I'm working on automating builds of thrift for Alpine Linux 3.8, and they will likely require "make check" to pass successfully in future versions. Might as well ensure it works now.

```

make[5]: Entering directory '/home/cfriedt/Desktop/thrift-20180627/lib/cpp/test'
Running 54 test cases...
An error message from getaddrinfo on the console is expected:
Thrift: Wed Jun 27 20:16:03 2018 getaddrinfo -2: Name or service not known

• • • No errors detected
      PASS: UnitTests
      Running 2 test cases...
      Thrift: Wed Jun 27 20:16:10 2018 ~TFDTransport TTransportException: 'TFDTransport::close(): Bad file descriptor'

• • • No errors detected
      PASS: TFDTransportTest
      Running 1 test case...

• • • No errors detected
      PASS: TPipedTransportTest
      Running 3 test cases...

• • • No errors detected
      PASS: DebugProtoTest
      Running 11 test cases...

• • • No errors detected
      PASS: JSONProtoTest
      Running 17 test cases...

• • • No errors detected
      PASS: OptionalRequiredTest
      Running 4 test cases...

• • • No errors detected
      PASS: RecursiveTest
      Running 1 test case...

• • • No errors detected
      PASS: SpecializationTest
      Running 3 test cases...
      TBinaryProtocol => OK
      TLEBinaryProtocol => OK
      TCompactProtocol => OK

• • • No errors detected
      PASS: AllProtocolsTest
      Running 285 test cases...
      Timeout alarm expired; attempting to unblock transport
      Timeout alarm expired; attempting to unblock transport
      Timeout alarm expired; attempting to unblock transport
      Timeout alarm expired; attempting to unblock transport
      Timeout alarm expired; attempting to unblock transport
      ^CMakefile:1436: recipe for target 'check-TESTS' failed
      make[5]: *** [check-TESTS] Interrupt
      Makefile:1559: recipe for target 'check-am' failed
      make[4]: *** [check-am] Interrupt
      Makefile:1562: recipe for target 'check' failed
      make[3]: *** [check] Interrupt
      Makefile:1658: recipe for target 'check-recursive' failed
      make[2]: *** [check-recursive] Interrupt
      Makefile:580: recipe for target 'check-recursive' failed
      make[1]: *** [check-recursive] Interrupt
      Makefile:663: recipe for target 'check-recursive' failed
      make: *** [check-recursive] Interrupt

```