qt5base: Build config change for PyQt5

[ar664]

In regards to my issue termux/termux-packages#10104 . I'm still trying to get PyQt5 to build on termux.

[ar664]

@xtkoba Is it possible to choose which architecture I want to build in the workflow? I'm just working on aarch64 right now, in this draft.

[xtkoba]

CI runs for all 4 architectures. But you can temporarily set TERMUX_PKG_BLACKLISTED_ARCHES:

TERMUX_PKG_BLACKLISTED_ARCHES="arm, i686, x86_64"

CI for an excluded arch normally finishes in 3 to 4 minutes.

[xtkoba]

I see the following lines in $PREFIX/include/QtCore/qtcore-config.h of the artifact:

#define QT_FEATURE_sharedmemory -1
#define QT_NO_SHAREDMEMORY

and

#define QT_FEATURE_systemsemaphore -1
#define QT_NO_SYSTEMSEMAPHORE

I doubt if this PR improves the situation for termux/termux-packages#10104.

I have enabled these features in qt5-qtbase version 5.15.3-1. Please rebase if any further changes are needed.

I also doubt if -system-proxies improves anything with respect to exported symbols.