Move regs-related macros and declarations from defs.h to regs.h

Move regs-related macros and declarations from defs.h to regs.h

* regs.h: New file.
* Makefile.am (strace_SOURCES): Add it.
* linux/arch_regs.h: New file.
* linux/alpha/arch_regs.h: Likewise.
* linux/arm/arch_regs.h: Likewise.
* linux/hppa/arch_regs.h: Likewise.
* linux/i386/arch_regs.h: Likewise.
* linux/ia64/arch_regs.h: Likewise.
* linux/mips/arch_regs.h: Likewise.
* linux/powerpc/arch_regs.h: Likewise.
* linux/sh64/arch_regs.h: Likewise.
* linux/sparc/arch_regs.h: Likewise.
* linux/sparc64/arch_regs.h: Likewise.
* linux/tile/arch_regs.h: Likewise.
* linux/x86_64/arch_regs.h: Likewise.
* Makefile.am (EXTRA_DIST): Add them.
* defs.h: Remove definitions of PTRACE_*, REG_*, PT_*, U_REG_*,
and ARM_* macros.
Remove declarations of struct pt_regs variables.
[SPARC]: Do not include <asm/psr.h>.
[SPARC64]: Do not include <asm/psrcompat.h>.
* bjm.c: Do not include <sys/user.h>.
* process.c: Include "regs.h".
Do not include <sys/user.h> and <sys/reg.h>.
[IA64]: Do not include <asm/ptrace_offsets.h> and <asm/rse.h>.
* util.c: Likewise.
* syscall.c: Likewise.
[AARCH64]: Define struct arm_pt_regs and ARM_* macros.
[SPARC]: Include <asm/psr.h>.
[SPARC64]: Include <asm/psrcompat.h>.
* signal.c: Include "regs.h".
Do not include <sys/user.h> and <sys/reg.h>.
[IA64]: Do not include <asm/ptrace_offsets.h>.
* strace.c [IA64]: Do not include <asm/ptrace_offsets.h>.