QLibrary: find AVX2 (Haswell) optimized plugins and libraries

Libraries are placed in a subdir "haswell/" of the main library dir,
whereas plugins are simply named with ".avx2" appended to the plugin
name (plugin.so.avx2). The "haswell/" library directory suffix is a
convention found in glibc since version 2.26, whereas the ".avx2" and
".avx512" suffixes are a convention found in the Clear Linux OS for
Intel Architecture.

This patch implements this for all Unix OSes, except for Darwin, where
the fat file format already has a sub-architecture for Haswell
(x86_64h).

We could also implement the "sse2/" subdir search for libraries, but I
don't think it's worth the cost in 2018.

Change-Id: Iff4151c519c144d580c4fffd1539fe5ee9a4d7b1
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions