Adds loongarch simd extension(LSX LASX) configure test and
-feature-lsx and -feature-lasx configure options.
Add detection of LSX and LASX at run-time in qsimd.cpp.
Change-Id: I63eab2f4f45c306b672a89b376e0cbc01da0df83
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
