PR 19051: support of inferior call with gnu vector support on ARM

PR 19051: support of inferior call with gnu vector support on ARM

This patch teaches GDB to support gnu vector in inferior calls.  As a
result, fails in gdb.base/gnu_vector.exp are fixed.  The calling
convention of gnu vector isn't documented in the AAPCS, because it
is the GCC extension.  I checked the gcc/config/arm/arm.c, understand
how GCC pass arguments and return values, and do the same in GDB side.

The patch is tested with both hard float and soft float on arm-linux.

gdb:

2015-11-13  Yao Qi  <yao.qi@linaro.org>

	PR tdep/19051
	* arm-tdep.c (arm_type_align): Return the right alignment
	value for vector.
	(arm_vfp_cprc_sub_candidate): Return true for 64-bit and
	128-bit vector types.
	(arm_return_in_memory): Handel vector type.