Revert "Include qsimd.cpp in bootstrap build"

This reverts commit 9268cb8085. That was
done in the mistaken assumption that the bootstrap library needs the
fast hashing algorithms. It doesn't, since it's only used for tools that
need deterministic output anyway.

This fixes the build on x86 where the compiler is enabling rdrand by
default (Ivy Bridge systems, but also -march=haswell and the GCC 11
-march=x86-64-v3):

qsimd.cpp:750:37: error: redefinition of ‘qsizetype qRandomCpu(void*, qsizetype)’
  750 | QT_FUNCTION_TARGET(RDRND) qsizetype qRandomCpu(void *buffer, qsizetype count) noexcept
      |                                     ^~~~~~~~~~
In file included from qsimd.cpp:44:
qsimd_p.h:354:25: note: ‘qsizetype qRandomCpu(void*, qsizetype)’ previously defined here
  354 | static inline qsizetype qRandomCpu(void *, qsizetype) noexcept
      |                         ^~~~~~~~~~

Change-Id: I755911ae7d0341f49039fffd167afc7540bf0dd6
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/tools/bootstrap/CMakeLists.txt

@@ -19,7 +19,6 @@ qt_internal_extend_target(Bootstrap
         ../../corelib/global/qnumeric.cpp
         ../../corelib/global/qoperatingsystemversion.cpp
         ../../corelib/global/qrandom.cpp
-        ../../corelib/global/qsimd.cpp
         ../../corelib/io/qabstractfileengine.cpp
         ../../corelib/io/qbuffer.cpp
         ../../corelib/io/qdebug.cpp