QtTest: fix build with MinGW/GCC 9: no std::mutex support

Unfortunately we can't depend on the C++11, 14 or 17 Standard
Library, which is not properly and completely implemented
everywhere. All Library features above C++98 must be checked with
their corresponding __cpp_lib macro before use. This does not
apply to the C++17 Core Language.

qwaitcondition_p.h:144:20: error: 'mutex' in namespace 'std' does not name a type
  144 | using mutex = std::mutex;
      |                    ^~~~~
qwaitcondition_p.h:59:1: note: 'std::mutex' is defined in header '<mutex>'; did you forget to '#include <mutex>'?
   58 | #include <condition_variable>
  +++ |+#include <mutex>
   59 | #include <mutex>
qwaitcondition_p.h:145:33: error: 'condition_variable' in namespace 'std' does not name a type
  145 | using condition_variable = std::condition_variable;
      |                                 ^~~~~~~~~~~~~~~~~~
qwaitcondition_p.h:59:1: note: 'std::condition_variable' is defined in header '<condition_variable>'; did you forget to '#include <condition_variable>'?
   58 | #include <condition_variable>
  +++ |+#include <condition_variable>
   59 | #include <mutex>

Pick-to: 6.2
Change-Id: I2bbf422288924c198645fffd16a9249e5330136a
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions