I'm trying to enable clang's -Wmissing-variable-declarations warning.
This patch fixes all the obvious spots where we can simply add "static"
(at least, found when building on x86-64 Linux).

gdb/ChangeLog:

	* aarch64-linux-tdep.c (aarch64_linux_record_tdep): Make static.
	* aarch64-tdep.c (tdesc_aarch64_list, aarch64_prologue_unwind,
	aarch64_stub_unwind, aarch64_normal_base, ): Make static.
	* arm-linux-tdep.c (arm_prologue_unwind): Make static.
	* arm-tdep.c (struct frame_unwind): Make static.
	* auto-load.c (auto_load_safe_path_vec): Make static.
	* csky-tdep.c (csky_stub_unwind): Make static.
	* gdbarch.c (gdbarch_data_registry): Make static.
	* gnu-v2-abi.c (gnu_v2_abi_ops): Make static.
	* i386-netbsd-tdep.c (i386nbsd_mc_reg_offset): Make static.
	* i386-tdep.c (i386_frame_setup_skip_insns,
	i386_tramp_chain_in_reg_insns, i386_tramp_chain_on_stack_insns):
	Make static.
	* infrun.c (observer_mode): Make static.
	* linux-nat.c (sigchld_action): Make static.
	* linux-thread-db.c (thread_db_list): Make static.
	* maint-test-options.c (maintenance_test_options_list):
	* mep-tdep.c (mep_csr_registers): Make static.
	* mi/mi-cmds.c (struct mi_cmd_stats): Remove struct type name.
	(stats): Make static.
	* nat/linux-osdata.c (struct osdata_type): Make static.
	* ppc-netbsd-tdep.c (ppcnbsd_reg_offsets): Make static.
	* progspace.c (last_program_space_num): Make static.
	* python/py-param.c (struct parm_constant): Remove struct type
	name.
	(parm_constants): Make static.
	* python/py-record-btrace.c (btpy_list_methods): Make static.
	* python/py-record.c (recpy_gap_type): Make static.
	* record.c (record_goto_cmdlist): Make static.
	* regcache.c (regcache_descr_handle): Make static.
	* registry.h (DEFINE_REGISTRY): Make definition static.
	* symmisc.c (std_in, std_out, std_err): Make static.
	* top.c (previous_saved_command_line): Make static.
	* tracepoint.c (trace_user, trace_notes, trace_stop_notes): Make
	static.
	* unittests/command-def-selftests.c (nr_duplicates,
	nr_invalid_prefixcmd, lists): Make static.
	* unittests/observable-selftests.c (test_notification): Make
	static.
	* unittests/optional/assignment/1.cc (counter): Make static.
	* unittests/optional/assignment/2.cc (counter): Make static.
	* unittests/optional/assignment/3.cc (counter): Make static.
	* unittests/optional/assignment/4.cc (counter): Make static.
	* unittests/optional/assignment/5.cc (counter): Make static.
	* unittests/optional/assignment/6.cc (counter): Make static.

gdbserver/ChangeLog:

	* ax.cc (bytecode_address_table): Make static.
	* debug.cc (debug_file): Make static.
	* linux-low.cc (stopping_threads): Make static.
	(step_over_bkpt): Make static.
	* linux-x86-low.cc (amd64_emit_ops, i386_emit_ops): Make static.
	* tracepoint.cc (stop_tracing_bkpt, flush_trace_buffer_bkpt,
	alloced_trace_state_variables, trace_buffer_ctrl,
	tracing_start_time, tracing_stop_time, tracing_user_name,
	tracing_notes, tracing_stop_note): Make static.

Change-Id: Ic1d8034723b7802502bda23770893be2338ab020