New target check for double<->int conversions

New target check for double<->int conversions

gcc/ChangeLog:

2017-10-04  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* doc/sourcebuild.texi: Document vect_intdouble_cvt and
	vect_doubleint_cvt.

gcc/testsuite/ChangeLog:

2017-10-04  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.dg/vect/pr66251.c: Replace vect_floatint_cvt with
	vect_doubleint_cvt and vect_intfloat_cvt with vect_intdouble_cvt.
	* gcc.dg/vect/vect-floatint-conversion-2.c: Replace
	vect_floatint_cvt with vect_doubleint_cvt.
	* gcc.dg/vect/vect-intfloat-conversion-3.c: Replace
	vect_intfloat_cvt with vect_intdouble_cvt.
	* gfortran.dg/vect/pr60510.f: Require vect_intdouble_cvt.
	* gfortran.dg/vect/vect-8.f90: Make number of vectorized loops
	depend on vect_intdouble_cvt.
	* lib/target-supports.exp
	(check_effective_target_vect_doubleint_cvt)
	(check_effective_target_vect_intdouble_cvt): New procs.

From-SVN: r253406