This patch enables more numeric (mod, sum, matmul, etc.) APIs,
and some others.
I added new macros to disable warnings about using C++ STD methods
like operators of std::complex, which do not have __device__ attribute.
This may probably result in unresolved references, if the header files
implementation relies on libstdc++. I will need to follow up on this.
Create a new flang/runtime/support.cpp module to hold miscellaneous
runtime APIs to support lowering, and define an API IsContiguous() to
wrap the member function predicate Descriptor::IsContiguous().
And do a little clean-up of other API headers that don't need to expose
Runtime/descriptor.h.
Differential Revision: https://reviews.llvm.org/D114752