The msvc linker had been warning about libcmt being dragged
in for a bit, finally tracked the issue down to the deps of
jpeg and pthreads which both ignored our cflags.
this diff changes them both to use the dynamic crt rather
than the static one so they'll be in line with all our
other libraries.
Note these are intended for platform maintainers, we do not intend to
support users making their own builds with these. For that precompiled
libraries from lib/ should be used.
Implemented by Martijn Berger, Ray Molenkamp and Brecht Van Lommel.
Differential Revision: https://developer.blender.org/D2753
