i386: Don't convert stack operations to pushes if using a redzone.

i386: Don't convert stack operations to pushes if using a redzone.

	* config/i386/i386-protos.h (ix86_using_red_zone): Declare.
	* config/i386/i386.c (ix86_using_red_zone): No longer static.
	* config/i386/i386.md (stack decrement to push peepholes): Guard
	with !x86_using_red_zone ().

testsuite/
	* gcc.target/i386/pr46470.c: Add -mno-red-zone to dg-options for
	x86_64.

From-SVN: r235028