Support --enable-hip on PGI/NVHPC

[Dan Bonachea]

As described in issue #531, there is some potential interest in running hip_device on NVIDIA GPU hardware, which opens up the possibility that a system of interest might support both HIP codes and a vendor-provided PGI/NVHPC compiler. Summit is already one such system

UPC++ configure --enable-hip currently hard-codes some GNU-like compiler options that choke PGI/NVHPC. We should explore improving this, at least providing an override for UPCXX_HIP_CPPFLAGS

[Dan Bonachea]

Mass roll-over of open issues to next release milestone

[Dan Bonachea]

Mass roll-over of open issues to next release milestone

[Dan Bonachea]

issue #532: Support --enable-hip on PGI/NVHPC

• UPCXX_HIP_CPPFLAGS defaulting modified to account for PGI and NVHPC compilers

• New configure -with-hip-cppflags option can override setting

• Documentation updates

Resolves issue #532

→ <<cset 6554ec38949c>>