[patch] Spelling fixes

[Jim Blandy]

Fred Fish <fnf@specifix.com> writes:
> Checked in under the 'obvious fix rule', though not sure if current
> practice is to record in ChangeLog or not.
>
> 2006-05-19  Fred Fish  <fnf@specifix.com>
>
> 	* Makefile.in: Fix spelling of 'explicitly' and 'explicit'.
> 	* dwarfread.c: Fix spelling of 'unexpected'.
> 	* mips-tdep.c: Fix spelling of 'possible' and 'Determine'.
> 	* stack.c: Fix spelling of 'RETURN_VALUE'.

Obvious changes to comments just need a log entry saying 'Doc fixes.'