test/driver: disable libjpeg-turbo SIMD support under Valgrind
test/driver: disable libjpeg-turbo SIMD support under Valgrind

The libjpeg-turbo maintainer reports that Valgrind has trouble tracking
memory initialization by the libjpeg-turbo SIMD code.  Disable the SIMD
code under Valgrind.

Fixes hamamatsu-ndpi-2012 extended test Valgrind failures with
"Conditional jump or move depends on uninitialised value(s)".

Signed-off-by: Benjamin Gilbert <55d1d0083477f6dd5757d8929dd3b9e09d80bd84@cs.cmu.edu>

openslide/openslide,openslide/openslide,openslide/openslide,openslide/openslide