Merge branch 'fixMemcpyOverlap' of github.com:hildeth/chapel into fixMemcpyOverlap

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Back dest==src test out of chpl_memcpy().

When -Werror=uninitialized is tossed, GCC complains about the version of chpl_memcpy()
where memcpy() is called only if dest and src differ.  It apparently does not reason that
dest is valid since it is already equal to src.  So I backed out the aggressive
conditional call to the system memcpy, and instead moved the dest != src test back to
chpl_gen_comm_get().

I also noticed that code used in building the launcher cannot see the definition of
chpl_memcpy(), so I reverted those calls to being direct calls to the system memcpy().

TODO: We may still get hung up on the assert, in which case we can address the cases
proactively rather than waiting for valgrind to flag them.
Merge branch 'master' into fixMemcpyOverlap
Merge pull request #759 from hildeth/fixMemcpyOverlap

Fix memcpy overlap tail

Greg's suggested change did not work with CHPL_COMM=gasnet, so I backed it out.

Also, when building launcher code, chpl_memcpy is not defined, so I reverted the memcpy --> chpl_memcpy change as needed.