[mythtv] macOS compile error by 1263ee2

[Piotr Oniszczuk]

David,

FYI:
https://github.com/MythTV/mythtv/commit/1263ee2c0b9200889b399214853925a9212697ca#diff-700d79812c59ba30d4068a012dac089e

causing me following compile error on macOSX 10.13.6, Xcode 10A255, Qt5.11.1

ccache /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -c -pipe -stdlib=libc++ -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DPIC -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -mmacosx-version-min=10.9 -I/Users/piotro/Devel/mythtv-master/.osx-packager/build/include -I/Users/piotro/Devel/mythtv-master/.osx-packager/build/mysql -std=c++11 -DNDEBUG -fomit-frame-pointer -fPIC -DQT_DISABLE_DEPRECATED_BEFORE=0x040800 -msse -pthread -g -Wall -Wextra -Wpointer-arith -D__STDC_CONSTANT_MACROS -D__STDC_LIMIT_MACROS -Wno-constant-logical-operand -Wno-unused-value -Qunused-arguments -Wimplicit-fallthrough -faligned-allocation -std=gnu++11  -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -mmacosx-version-min=10.11 -fPIC -DMMX -DUSING_APPLEREMOTE -D_GNU_SOURCE -DSERVICE_API -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_SCRIPT_LIB -DQT_CORE_LIB -I. -I../libmythbase -Ienums -Idatacontracts -Iservices -I../libmyth -I../libmythbase -I/Users/piotro/Devel/Qt5.11.1SDK/5.11.1/clang_64/lib/QtGui.framework/Headers -I/Users/piotro/Devel/Qt5.11.1SDK/5.11.1/clang_64/lib/QtScript.framework/Headers -I/Users/piotro/Devel/Qt5.11.1SDK/5.11.1/clang_64/lib/QtCore.framework/Headers -Imoc -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/OpenGL.framework/Headers -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/AGL.framework/Headers -I/Users/piotro/Devel/Qt5.11.1SDK/5.11.1/clang_64/mkspecs/macx-clang -F/Users/piotro/Devel/Qt5.11.1SDK/5.11.1/clang_64/lib -o obj/moc_programList.o moc/moc_programList.cpp
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
util-osx.cpp:53:16: error: cannot initialize return object of type 'CGDirectDisplayID' (aka 'unsigned int') with an rvalue of type 'nullptr_t'
        return nullptr;
               ^~~~~~~
1 warning and 1 error generated.
make[2]: *** [obj/util-osx.o] Error 1
make[2]: *** Waiting for unfinished jobs….