(output_init_element): Don't call default_conversion for a STRING_CST if type is...

(output_init_element): Don't call default_conversion for a STRING_CST if type is directly suitable for it.

(output_init_element): Don't call default_conversion
for a STRING_CST if type is directly suitable for it.
(digest_init): Eliminate a lot of code that checks the variable
'element', since element is always 0 in these code paths.

(build_c_cast): For (void *) (FOO *) 0, return a nop_expr
so it doesn't count as a null pointer constant.
(convert_for_assignment, build_binary_op): Pedantically warn about
that case if looking for a null_pointer_constant.
(build_conditional_expr): Likewise.

From-SVN: r5150