[tree-ssa] Bootstrap failure on alpha

[Jan Hubicka]

> 
> Jan,
> 
> One of these two patches introduced a bootstrap regression in alpha. 
> -Werror is triggered for the stage1 compiler when building cppcharset.c

This is the same problem as in other two warnings.  The function
one_utf8_to_cppchar takes s as reference.  This used to count as
initialization, but now we inline the function and we realize that there
is path trought the function not initializing s.  I will commit the
patch to iniitialize s to 0 as obivous to both mainline and branch as we
did for the other case.

Honza