[GPUJIT] Add GPUJIT APIs for allocating and freeing managed memory.
We introduce polly_mallocManaged and polly_freeManaged as
proxies for cudaMallocManaged / cudaFree. This is currently not
used by Polly. It is auxiliary code that is used in COSMO.
This is useful because polly_mallocManaged matches the signature of malloc,
while cudaMallocManaged does not. We introduce polly_freeManaged for
We use this in COSMO to use the unified memory feature of the newer
CUDA APIs (>= 6).
Differential Revision: https://reviews.llvm.org/D35991