Do not increment of decrement enums

Do not increment of decrement enums

In C++, we can't do arithmetic on enums.  This patch fixes build errors like:

 src/gdb/i386-tdep.c: In function ‘int i386_stap_parse_special_token(gdbarch*, stap_parse_info*)’:
 src/gdb/i386-tdep.c:4309:7: error: no match for ‘operator++’ (operand type is ‘i386_stap_parse_special_token(gdbarch*, stap_parse_info*)::<anonymous enum>’)
	++current_state;
	^
 ...
 src/gdb/rs6000-tdep.c:4265:18: error: no match for ‘operator++’ (operand type is ‘powerpc_vector_abi’)
 src/gdb/arm-tdep.c:9428:71: error: no match for ‘operator++’ (operand type is ‘arm_float_model’)
 src/gdb/arm-tdep.c:9465:64: error: no match for ‘operator++’ (operand type is ‘arm_abi_kind’)
 ...

gdb/ChangeLog:
2015-02-27  Tom Tromey  <tromey@redhat.com>
	    Pedro Alves <palves@redhat.com>

	* arm-tdep.c (set_fp_model_sfunc, arm_set_abi): Use 'int' for
	local used to iterate over enums.
	* completer.c (signal_completer): Likewise.
	* i386-tdep.c (i386_stap_parse_special_token): Likewise.
	* rs6000-tdep.c (powerpc_set_vector_abi): Likewise.
	* tui/tui-data.c (tui_next_win, tui_prev_win): Likewise.
	* tui/tui-layout.c (next_layout, prev_layout): Likewise.
	* tui/tui-win.c (tui_refresh_all_win, tui_rehighlight_all)
	(tui_resize_all, tui_set_focus_command, tui_all_windows_info): Likewise.
	* tui-wingeneral.c (tui_refresh_all):  Likewise.