Fix incorrect OpenMP version in Fortran module.

Add check for "45" version to use "201511" string for OpenMP 4.5,
otherwise "200505" is used in Fortran module. Also, fix kmp_openmp_version
variable (used for the debugger, e.g.) and kmp_version_omp_api that is used
in KMP_VERSION=1 output.

Patch by Olga Malysheva

Differential Revision: https://reviews.llvm.org/D24761

llvm-svn: 282868