Misc: minimal support of profiling interface

[minsii]

Similar to MPI profiling interface (PMPI), OpenSHMEM 1.5 defines pshmem_ wrapper and a query function shmem_pcontrol.

Starting point

• Section 10 OpenSHMEM Profiling Interface in OpenSHMEM spec v1.5
• Many type/size specific functions are generated at autogen.sh. Also see the template files (.tpl) under src/shmem. We may also autogenerate the pshmem_ wrapper.
• configure.ac already detects USE_WEAK_SYMBOLS
• Can reuse PMPI_ implementation.

TODO

• [ ] Implementation of pshmem_ weak symbol for all functions
• [ ] Implementation of shmem_pcontrol (NO-OP is fine)