gdb/remote.c: address conflicting enum and method name

gdb/remote.c: address conflicting enum and method name

When building with gcc 4.8, we get:

      CXX    remote.o
    cc1plus: warning: command line option '-Wmissing-prototypes' is valid for C/ObjC but not for C++ [enabled by default]
    /home/smarchi/src/binutils-gdb/gdb/remote.c:1157:38: error: 'resume_state' is not a class, namespace, or enumeration
       enum resume_state m_resume_state = resume_state::NOT_RESUMED;
                                          ^

It looks like gcc 4.8 doesn't like that there is an enum class named
resume_state as well as a method.  Since it's an easy fix, rename the method to
get_remote_state to avoid the clash.

gdb/ChangeLog:

	PR gdb/27219
	* remote.c (struct remote_thread_info) <resume_state>: Rename
	to...
	<get_resume_state>: ... this.
	(remote_target::resume): Adjust.
	(remote_target::commit_resume): Adjust.
	(remote_target::select_thread_for_ambiguous_stop_reply): Adjust.

Change-Id: Ib86c877a4c75ee671d69c27ed06cb8f57bc087db