[OPENMP] Fix PR38903: Crash on instantiation of the non-dependent

[OPENMP] Fix PR38903: Crash on instantiation of the non-dependent
declare reduction.

If the declare reduction construct with the non-dependent type is
defined in the template construct, the compiler might crash on the
template instantition. Reworked the whole instantiation scheme for the
declare reduction constructs to fix this problem correctly.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@342151 91177308-0d34-0410-b5e6-96231b3b80d8