WebAssembly: FTBFS on macOS because features.h not found

Run ./configure -release -prefix /usr/local/opt/qt-wasm -xplatform wasm-emscripten -qt-host-path /usr/local/opt/qt in qt-everywhere-src/

Then cmake --build .

Outputs:

[220/12416] Building CXX object qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/_/_/corelib/global/qmalloc.cpp.o
FAILED: qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/_/_/corelib/global/qmalloc.cpp.o
/usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++ -DGL_SILENCE_DEPRECATION -DHAVE_CONFIG_H -DQT_BOOTSTRAPPED -DQT_NO_CAST_FROM_ASCII -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_NO_FOREACH -DQT_USE_QSTRINGBUILDER -DQT_VERSION_MAJOR=6 -DQT_VERSION_MINOR=1 -DQT_VERSION_PATCH=1 -DQT_VERSION_STR=\"6.1.1\" -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -Iqtbase/src/corelib/Core_autogen/include -Iqtbase/include -Iqtbase/include/QtCore -Iqtbase/lib/QtCore.framework/Headers -Iqtbase/src/corelib -Iqtbase/src/corelib/global -Iqtbase/src/corelib/kernel -Iqtbase/src/corelib/../3rdparty/tinycbor/src -Iqtbase/include/QtCore/6.1.1 -Iqtbase/include/QtCore/6.1.1/QtCore -Iqtbase/src/corelib/../3rdparty/forkfd -Iqtbase/src/corelib/.rcc -Iqtbase/mkspecs/wasm-emscripten -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -Iqtbase/src/xml/Xml_autogen/include -Iqtbase/include/QtXml -Iqtbase/lib/QtXml.framework/Headers -Iqtbase/src/xml -Iqtbase/include/QtXml/6.1.1 -Iqtbase/include/QtXml/6.1.1/QtXml -Iqtbase/src/tools/bootstrap/.. -Iqtbase/src/tools/bootstrap/../../3rdparty/tinycbor/src -DNDEBUG -O2 -isysroot /Applications/Xcode_12.5.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk -mmacosx-version-min=10.14 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -ffunction-sections -fdata-sections -std=gnu++17 -MD -MT qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/_//corelib/global/qmalloc.cpp.o -MF qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir///corelib/global/qmalloc.cpp.o.d -o qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir//_/corelib/global/qmalloc.cpp.o -c qtbase/src/corelib/global/qmalloc.cpp
In file included from qtbase/src/corelib/global/qmalloc.cpp:40:
qtbase/mkspecs/wasm-emscripten/qplatformdefs.h:57:10: fatal error: 'features.h' file not found
#include <features.h>
^~~~~~~~~~~~
1 error generated.

In file included from qtbase/src/corelib/global/qglobal.cpp:41:
qtbase/mkspecs/wasm-emscripten/qplatformdefs.h:57:10: fatal error: 'features.h' file not found
#include <features.h>
^~~~~~~~~~~~
1 error generated.
1 error generated.
ninja: build stopped: subcommand failed.

 macOS doesn't provide features.h.