(fold_truthop): Treat a BIT_AND_EXPR with a constant of one as if it were

(fold_truthop): Treat a BIT_AND_EXPR with a constant of one as if it were
surrounded with an NE_EXPR.
(fold): Don't move operation into conditional if it is BIT_{AND,OR}_EXPR with
the constant 1; change it to TRUTH_*_EXPR instead.
When moving things inside conditions, move comparisons as well as binary
operations.
Don't make a SAVE_EXPR when moving things inside conditionals unless the value
would really have been used twice.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@4746 138bc75d-0d04-0410-961f-82ee72b054a4