some oshmem files missing from tarball when configuring with --disable-oshmem

[hjelmn]

This is the norm when built on a mac. If I try to build and install the tarball on another machine it fails when it get to installing the oshmem man pages. Looking at oshmem/shmem/man/man3 I see:

tt-fey1:/scratch1/hjelmn/openmpi-gitclone/oshmem/shmem/man/man3 hjelmn$ ls
Makefile.extra

This started with the fix that prevents oshmem man pages from being installed when oshmem is disabled. They should still be included in the tarball generated by make dist. Maybe add the files to EXTRA_DIST?

[hjelmn]

@miked-mellanox Please assign to the appropriate person. To reproduce configure with --disable-oshmem and then make dist.

[mike-dubman]

@igor-ivanov - please take a look. thanks

[ggouaillardet]

imho, this is a much more general issue

for example, if you configure with --disable-mpi there are no source file in the /ompi directory (!)

[mike-dubman]

@igor-ivanov - could you please PR it to v2.x as well
thanks