Remove some hard-coded stuff in tests

Remove some hard-coded stuff in tests

There are some hard-coded stuff in .s files, such as .int 0 and
address offset, which isn't portable.  This patch is to replace
".int 0" with nop and address offset with labels.

gdb/testsuite:

2015-03-26  Yao Qi  <yao.qi@linaro.org>

	* gdb.linespec/break-asm-file0.s (func2): Use nop instead of
	.int 0.
	(func): Likewise.  Add .Lfunc_1 label.
	Use .Lfunc_1 label.
	* gdb.linespec/break-asm-file1.s (func3): Use nop instead of
	.int 0.
	(func): Likewise.
	Use .Lfunc_1 label.