x86: signal: move {setup|restore}_sigcontext()

Status from this message: applied to tip/x86/signal, thanks Hiroshi!

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#	Subject and files	Size	Replies
1/3	x86: signal: move {setup\|restore}_sigcontext()`arch/x86/kernel/signal_32.c` `arch/x86/kernel/signal_64.c`	+210 ~~-209~~	0 replies
2/3	x86: signal: cosmetic unification of __setup_sigframe() and __setup_rt_sigframe()`arch/x86/kernel/signal_32.c` `arch/x86/kernel/signal_64.c`	+536 ~~-242~~	0 replies
3/3	x86: signal: unify signal_{32\|64}.c`arch/x86/kernel/Makefile` `arch/x86/kernel/signal.c` `arch/x86/kernel/signal_32.c` +1 more	+916 ~~-1711~~	2 replies

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