Add -malign-data={abi|compat,cachineline} to control how GCC aligns
variables.  "compat" uses increased alignment value compatible with
GCC 4.8 and earlier, "abi" uses alignment value as specified by the
psABI, and "cacheline" uses increased alignment value to match the
cache line size.  "compat" is the default.

gcc/

	PR target/61296
	* config/i386/i386-opts.h (ix86_align_data): New enum.
	* config/i386/i386.c (ix86_data_alignment): Return the ABI
	alignment value for -malign-data=abi, the cachine line size
	for -malign-data=cachineline and the older GCC compatible
	alignment value for for -malign-data=compat.
	* config/i386/i386.opt (malign-data=): New.
	* doc/invoke.texi: Document -malign-data=.

gcc/testsuite/

	PR target/61296
	* gcc.target/i386/pr61296-2.c: New.
	* gcc.target/i386/pr61296-2.c: Likewise.
	* gcc.target/i386/pr61296-3.c: Likewise.
	* gcc.target/i386/pr61296-4.c: Likewise.
	* gcc.target/i386/pr61296-5.c: Likewise.
	* gcc.target/i386/pr61296-6.c: Likewise.
	* gcc.target/i386/pr61296-7.c: Likewise.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>
Co-Authored-By: Uros Bizjak <ubizjak@gmail.com>

From-SVN: r218818