hdf5

[svn-r13138] Description:
	Auto-detect the support for the posix_memalign routine and disable
the direct I/O VFD if posix_memalign is not supported.  This should allow
direct I/O to be auto-detected and disabled on FreeBSD.  (Direct I/O itself
works fine, but doesn't have the alignment requirements on FreeBSD that it
has on Linux, so the code would have to be re-worked to not use posix_memalign
and we don't need to support that right now).

Tested on:
	FreeBSD/32 6.1 (duty)
	Linux/32 2.4 (kagiso)