Introduce a new WIN32_REDIST_OPENMP_DIR build variable which points to
the location where vcomp110.dll can be found. If WIN32_REDIST_DIR is
defined (can be in .mozconfig), the value of WIN32_REDIST_OPENMP_DIR
will be automatically derived from it.
Make sure that vcomp110.dll follows suit anywhere the CRT libraries are
being handled in the build process.
This only applies when building using Visual Studio 2012.
rhinoduck
282c8c1ea4