Per today's telecon, turn off oshmem by default
Fixes #4364: Move r30998 to v1.7 branch (Add a couple of NEWS)

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r30998 [[BR]]
Add a couple of NEWS bullets in prep for 1.7.5 release

cmr=v1.7.5:reviewer=ompi-gk1.7
Fixes #4362: Move r30995 to v1.7 branch (OSHMEM: various fixes)

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r30995 [[BR]]
OSHMEM: various fixes

- -check-shmem-params is OFF by default. It checks OSHMEM API params and will abort on bad input
- hcoll do not save fallback coll pointers for unsupported collectives.

fixed by Val, Roman, reviewed by Miked/Igor

cmr=v1.7.5:reviewer=ompi-rm1.7
1.7.5rc1 was released a little while ago; on to 1.7.5rc2