PR63426 Fix various signed integer overflows

Running the testsuite after bootstrap-ubsan on gcc112 shows several issues. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63426 for the full list.

This patch fixes several of them.

2014-11-20  Markus Trippelsdorf  <markus@trippelsdorf.de>

	* config/rs6000/constraints.md: Avoid signed integer overflows.
	* config/rs6000/predicates.md: Likewise.
	* config/rs6000/rs6000.c (num_insns_constant_wide): Likewise.
	(includes_rldic_lshift_p): Likewise.
	(includes_rldicr_lshift_p): Likewise.
	* emit-rtl.c (const_wide_int_htab_hash): Likewise.
	* loop-iv.c (determine_max_iter): Likewise.
	(iv_number_of_iterations): Likewise.
	* tree-ssa-loop-ivopts.c (get_computation_cost_at): Likewise.
	* varasm.c (get_section_anchor): Likewise.

From-SVN: r217886