[lib] Make message lookup function more robust.

[lib] Make message lookup function more robust.

2007-03-20 Andrew J. Schorr <ajschorr@alumni.princeton.edu>

	* log.c: (mes_lookup) Make the function more robust: check for
	  cases where the index does not match the key value at that position.
	  If so, give a warning and fall back to a linear search.
	  And improve the error message in cases where even that fails.