hdf5_msb

[svn-r16394] Description:
	Rename H5O_msg_read_real -> H5O_msg_read_oh, to be more consistent with
other routines in library.

	Move H5O_msg_read_oh and H5O_msg_exists_oh from package to private
header file, so other routines in library can use them.

Tested on:
	FreeBSD/32 6.3 (duty)
	Too minor to require h5committest