bug#10867: 23.4 must export LC_CTYPE to zh_CN.UTF-8 or similar CJK locale to use X input method

[Weng Xuetian]

This bug has existing for a long time. Ever since serveral years ago.
I'm not talking about built in input method, but XIM, which can be provided by 
fcitx, gcin, scim, or ibus.

Since this bug existing for a long time, I think that'some of the reason that 
scim and ibus provides scim-el and ibus-el to make emacs works with input 
method under non-CJK locale.

There is no limitation for XIM to work with non-CJK locale, since xterm, or 
something similar already can works well.

Or emacs should change the input method support code to gtk input context.

Reproduce step:
1. set locale to en_US.UTF-8, start emacs, X input method do not work.
2. set locale to zh_CN.UTF-8, start emacs, X input method now works.