[ARM][PR82989] Fix unexpected use of NEON instructions for shifts

[ARM][PR82989] Fix unexpected use of NEON instructions for shifts

This is a backport of r258677 and r258723 of trunk.

*** gcc/ChangeLog ***

2018-03-27  Sudakshina Das  <sudi.das@arm.com>

	Backport from mainline:
	2018-03-20  Sudakshina Das  <sudi.das@arm.com>

	PR target/82989
	* config/arm/neon.md (ashldi3_neon): Update ?s for constraints
	to favor GPR over NEON registers.
	(<shift>di3_neon): Likewise.

*** gcc/testsuite/ChangeLog ***

2018-03-27  Sudakshina Das  <sudi.das@arm.com>

	Backport from mainline:
	2018-03-20  Sudakshina Das  <sudi.das@arm.com>

	PR target/82989
	* gcc.target/arm/pr82989.c: New test.

	Backport from mainline:
	2018-03-21  Sudakshina Das  <sudi.das@arm.com>

	PR target/82989
	* gcc.target/arm/pr82989.c: Change dg scan-assembly directives.

From-SVN: r258884