slp-11.c: Split into...

gcc/testsuite/
	* gcc.dg/vect/slp-11.c: Split into...
	* gcc.dg/vect/slp-11a.c, gcc.dg/vect/slp-11b.c,
	gcc.dg/vect/slp-11c.c: ...these tests.
	* gcc.dg/vect/slp-12a.c: Split 4-stride loop into...
	* gcc.dg/vect/slp-12c.c: ...this new test.
	* gcc.dg/vect/slp-19.c: Split into...
	* gcc.dg/vect/slp-19a.c, gcc.dg/vect/slp-19b.c,
	gcc.dg/vect/slp-19c.c: ...these new tests.

From-SVN: r173294