[gfortran] Fix PR 19543: Type mismatch when building logical constants

[Tobias Schlüter]

Tobias Schlüter wrote:
> 2005-01-21  Tobias Schl"uter  <tobias.schlueter@physik.uni-muenchen.de>
> 
> 	PR fortran/19543
> 	* trans-const.c (gfc_conv_constant_to_tree): Give logical
> 	constants the correct type.

Putting together a testcase, I had to find out that this patch isn't
sufficient.  While the tree dumps look correct, constant merging seems to
wreak havoc in certain cases.  I'll add this information to the PR.

Supposing this is indeed a middle-end bug, would it be a good idea to submit
my patch anyway, so that the hypothetical middle-end hacker will not have to
patch his Fortran compiler to get a clear view of this issue?

- Tobi