[OpenMP] Change AAKernelInfo to ignore non-kernels

Currently, AAKernelInfo will fail on an assertion if we attempt to run
it on a kernel without the init / deinit runtime calls. However, this
occurs for global constructors on the device. This will cause OpenMPOpt
to crash whenever global constructors are present. This patch removes
this assertion and just gives up instead.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D108258