Change the prototype for the open() system call to agree with Posix. 
Though a faulty function prototype in a pointer cast is a seemingly innocuous
error, the correct prototype is necessary for pthreads to work correctly
on NetBSD.
Bump the version number to 3.7.6.2
Version 3.7.6.2
Backport the [67bf1c9a88] fix for vanishing WAL transactions due to small
cache spillage.  Ticket [2d1a5c67dfc236].  Also bump the version number
to 3.7.6.3 in preparation for patch release.
Version 3.7.6.3 release candidate 1.
Backport the localtime() failure fix of ticket [bd484a090c8077] to the
3.7.6 branch.
Give the osLocaltime() function file scope in date.c.
Backport the fixes for Coverity-discovered problems 
in [1c27d84216], [676acce274], and [f9c4a7c8f4] from trunk to the
3.7.6 branch.
Fix a problem with [f9c4a7c8f4] as applied to this branch.