Qt build segfaults due to infinite recursion in qDetectCpuFeatures

Probably introduced by commit 780137d585344bf9de906a285a50498104c0c66e

This seems to affect tools that are used in the build process. One example is src/tools/qvkgen:

(gdb) bt
#0  0x00007ffff7565cb0 in qCpuFeatures () at tools/qsimd_p.h:359
#1  0x00007ffff75667ee in qRandomCpu (buffer=0x7fffff7ff0a0, count=4) at tools/qsimd.cpp:671
#2  0x00007ffff7566242 in detectProcessorFeatures () at tools/qsimd.cpp:395
#3  0x00007ffff756634e in qDetectCpuFeatures () at tools/qsimd.cpp:570
#4  0x00007ffff7565cde in qCpuFeatures () at tools/qsimd_p.h:365
#5  0x00007ffff75667ee in qRandomCpu (buffer=0x7fffff7ff250, count=4) at tools/qsimd.cpp:671
#6  0x00007ffff7566242 in detectProcessorFeatures () at tools/qsimd.cpp:395
#7  0x00007ffff756634e in qDetectCpuFeatures () at tools/qsimd.cpp:570
#8  0x00007ffff7565cde in qCpuFeatures () at tools/qsimd_p.h:365
#9  0x00007ffff75667ee in qRandomCpu (buffer=0x7fffff7ff400, count=4) at tools/qsimd.cpp:671
#10 0x00007ffff7566242 in detectProcessorFeatures () at tools/qsimd.cpp:395
#11 0x00007ffff756634e in qDetectCpuFeatures () at tools/qsimd.cpp:570
#12 0x00007ffff7565cde in qCpuFeatures () at tools/qsimd_p.h:365
#13 0x00007ffff75667ee in qRandomCpu (buffer=0x7fffff7ff5b0, count=4) at tools/qsimd.cpp:671
#14 0x00007ffff7566242 in detectProcessorFeatures () at tools/qsimd.cpp:395