Remove d10v from testsuite

Remove d10v from testsuite

This patch removes the leftover of the d10v stuff in the testsuite
directory. The d10v port was removed in GDB 6.7, but I happen to see
that there are still some leftovers about d10v in testsuite.

gdb/testsuite:

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

	* gdb.base/call-sc.exp (test_scalar_returns): Remove the
	comments about d10v.
	(test_scalar_returns): Likewise.
	* gdb.base/d10v.ld: Remove.
	* gdb.base/overlays.exp: Remove the target triplet checking for
	d10v-*-*.
	* gdb.base/structs.exp (test_struct_returns): Remove the
	comments about d10v.
	(test_struct_calls): Likewise.