oshmem_info link failure in 4.0.1

[benmenadue]

oshmem_info fails to link in 4.0.1 on our system because of some missing symbols:

make[2]: Entering directory `/tmp/tmp.gfEN6slnF8/openmpi-4.0.1/gcc-opt/oshmem/tools/oshmem_info'
  CC       oshmem_info.o
  CC       param.o
  GENERATE oshmem_info.1
  CCLD     oshmem_info
../../../oshmem/.libs/liboshmem.so: undefined reference to `ctx_destroy'
../../../oshmem/.libs/liboshmem.so: undefined reference to `MCA_SPML_CALL'
../../../oshmem/.libs/liboshmem.so: undefined reference to `ctx_create'
collect2: ld returned 1 exit status
make[2]: *** [oshmem_info] Error 1
make[2]: Leaving directory `/tmp/tmp.gfEN6slnF8/openmpi-4.0.1/gcc-opt/oshmem/tools/oshmem_info'

We're running on a CentOS 6.10 userland and using the system compiler (gcc 4.4.7). It's a standard configure and make from the release tarball (after patching for #6560).

[benmenadue]

There's a missing #include in oshmem/shmem/c/shmem_context.c. This file was missing from the 4.0.0 build when the profiling interface was enabled (fixed by aaf15a6), which is why we didn't run into this previously.

Again, an easy fix, so I've patched it and will PR when the test build completes.