Fixes #4219: Move r30543 to v1.7 branch (Minor cleanup required when configuring)

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r30543 [[BR]]
Minor cleanup required when configuring with an external libevent. Thanks to Orion Poplawski for the patch!

cmr=v1.7.4:reviewer=ompi-gk1.7
Fixes #4218: Move r30542 to v1.7 branch (silence some solaris warnings)

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r30542 [[BR]]
Silence some Solaris warnings reported by Paul Hargrove

cmr=v1.7.4:reviewer=jsquyres:subject=Silence some Solaris warnings