Declare Lisp_Object Q* variables to be 'static' if not exproted.

Declare Lisp_Object Q* variables to be 'static' if not exproted.

This makes it easier for human readers (and static analyzers)
to see whether these variables are used from other modules.
* alloc.c, buffer.c, bytecode.c, callint.c, casetab.c, category.c:
* ccl.c, character.c, charset.c, cmds.c, coding.c, composite.c:
* data.c, dbusbind.c, dired.c, editfns.c, eval.c, fileio.c, fns.c:
* font.c, frame.c, fringe.c, ftfont.c, image.c, keyboard.c, keymap.c:
* lread.c, macros.c, minibuf.c, print.c, process.c, search.c:
* sound.c, syntax.c, textprop.c, window.c, xdisp.c, xfaces.c, xfns.c:
* xmenu.c, xselect.c:
Declare Q* vars static if they are not used in other modules.
* ccl.h, character.h, charset.h, coding.h, composite.h, font.h:
* frame.h, intervals.h, keyboard.h, lisp.h, process.h, syntax.h:
Remove decls of unexported vars.
* keyboard.h (EVENT_HEAD_UNMODIFIED): Remove now-unused macro.