objdump: set address of debug sections.

This patche fixes the values of FDE pc in output of objdump -Wf. They now
match readelf ones.

binutils/
	* objdump.c (load_specific_debug_section): Set address of section.
Return zero in can_single_step_to_signal_handler for nios2-*-* target

nios2 uses software single step, so GDB is unable to single step to
the signal handler.  In order to reflect this, teach
can_single_step_to_signal_handler to return zero for nios2 target.

gdb/testsuite:

2014-03-27  Yao Qi  <yao@codesourcery.com>

	* lib/gdb.exp (can_single_step_to_signal_handler): Return zero
	if target is nios2-*-*.