build fails on Ubuntu 18.04 due to zstd not knowing --single-thread

I'm cross-compiling on Ubuntu 18.04 amd64 with the latest MXE for i686-w64-mingw32.static and x86_64-w64-mingw32.static (MXE verbiage). For both architectures the build fails with the following error message:
 

perl /opt/mxe/tmp-qtbase-x86_64-w64-mingw32.static/qtbase-everywhere-src-5.15.0/src/corelib/mimetypes/mime/generate.pl --zstd mimetypes/mime/packages/freedesktop.org.xml > .rcc/release/qmimeprovider_database.cpp
Incorrect parameters
Failed to run zstd -cq19 --single-thread < mimetypes/mime/packages/freedesktop.org.xml at /opt/mxe/tmp-qtbase-x86_64-w64-mingw32.static/qtbase-everywhere-src-5.15.0/src/corelib/mimetypes/mime/generate.pl line 82.

The problem is that zstd on Ubuntu 18.04 is 1.3.3+dfsg-2ubuntu1.1 which doesn't support the "--single-thread" option yet.

After patching "generate.pl" and removing "--single-thread" from the invocation of zstd the build succeeds for both architectures.