[OpenMP][NVPTX] Disable OpenMPOpt when building deviceRTLs

We build `deviceRTLs` with `-O1` by default, which also triggers OpenMPOpt. When
the info cache is created, some attributes are removed. As a result, although we
mark a few functions `noinline`, they are still inlined when the bitcode library
is generated. This can cause an issue in middle end optimization.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D106710