Error building Qt 5.13.2 on macOS

Hi,

Today I tried to build 5.12.8, 5.13.2 and 5.14.2 with Xcode 11.4.1 on macOS 10.15.4.

I first applied the patch from https://bugreports.qt.io/browse/QTBUG-83318 to all three.

5.12.8 and 5.14.2 compile ok but 5.13.2 gives an error with futimens.

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -c -include.pch/debug/QtCore_debug/c+_x86_64 -pipe -stdlib=libc+ -g -std=c++1y -fapplication-extension  -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -mmacosx-version-min=10.12 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -W -Winconsistent-missing-override -Wobjc-interface-ivars -Wobjc-method-access -Wobjc-multiple-method-names -Werror=unguarded-availability -Werror=unguarded-availability-new -Werror=unsupported-availability-guard -fPIC -DQT_NO_USING_NAMESPACE -DQT_NO_FOREACH -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_BUILD_CORE_LIB -DQT_BUILDING_QT -DQT_NO_CAST_TO_ASCII -DQT_ASCII_CAST_WARNINGS -DQT_MOC_COMPAT -DQT_USE_QSTRINGBUILDER -DQT_DEPRECATED_WARNINGS -DQT_DISABLE_DEPRECATED_BEFORE=0x050000 -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DPCRE2_CODE_UNIT_WIDTH=16 -I. -Iglobal -I../3rdparty/harfbuzz/src -I../3rdparty/md5 -I../3rdparty/md4 -I../3rdparty/sha3 -I../3rdparty -I../3rdparty/double-conversion/include -I../3rdparty/double-conversion/include/double-conversion -I../3rdparty/forkfd -I../3rdparty/tinycbor/src -I../../include -I../../include/QtCore -I../../include/QtCore/5.13.2 -I../../include/QtCore/5.13.2/QtCore -I.moc/debug -I.tracegen/debug -I../3rdparty/pcre2/src -I../../mkspecs/macx-clang -o .obj/debug/qfilesystemengine_unix.o io/qfilesystemengine_unix.cpp

io/qfilesystemengine_unix.cpp:1404:9: error: 'futimens' is only available on macOS 10.13 or newer

      [-Werror,-Wunguarded-availability-new]

    if (futimens(fd, ts) == -1) {

        ^~~~~~~~

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include/sys/stat.h:396:9: note:

      'futimens' has been marked as being introduced in macOS 10.13 here, but the deployment target is macOS 10.12.0

int     futimens(int __fd, const struct timespec __times[2]) __API_AVAILABLE(macosx(10.13), ios(11.0), tvos(11.0), watchos(4.0));

        ^

io/qfilesystemengine_unix.cpp:1404:9: note: enclose 'futimens' in a __builtin_available check to silence this warning

    if (futimens(fd, ts) == -1) {

        ^~~~~~~~

1 error generated.

make[4]: *** [.obj/debug/qfilesystemengine_unix.o] Error 1

make[3]: *** [debug-all] Error 2

make[2]: *** [sub-corelib-make_first] Error 2

make[1]: *** [sub-src-make_first] Error 2

make: *** [module-qtbase-make_first] Error 2