Addition of OpenMP 4.5 feature: schedule(simd:static)

This patch implements the new kmp_sch_static_balanced_chunked schedule kind that
the compiler will generate when it encounters schedule(simd: static). It just
adds the new constant and the new switch case __kmp_for_static_init.

Patch by Alex Duran.

Differential Revision: http://reviews.llvm.org/D20699

llvm-svn: 271320