Allow GDB to run on Linux 2.0 again.
* config.in: Add HAVE_PTRACE_GETREGS.
* configure.in: Check if <sys/ptrace.h> defines PTRACE_GETREGS.
* configure: Regenerated.
* config/i386/nm-linux.h (CANNOT_FETCH_REGISTER,
CANNOT_STORE_REGISTER): New defines.
* i386-linux-nat.c (have_ptrace_getregs): New variable.
(PTRACE_XFER_TYPE, CANNOT_FETCH_REGISTER, fetch_register,
old_fetch_inferior_registers, CANNOT_STORE_REGISTER,
store_register, old_store_inferior_registers): Copied over from
`inptrace.c' as a temporary measure.
(fetch_regs, store_regs, fetch_fpregs, store_fpregs):
Conditionalize on HAVE_PTRACE_GETREGS. Define stubs if
HAVE_PTRACE_GETREGS isn't defined.
(fetch_regs): Reset `have_ptrace_getregs' if ptrace call fails
with EIO.
(fetch_inferior_registers, store_inferior_registers): Fall back on
the method use in `infptrace.c' (by calling
old_fetch_inferior_registers and old_store_inferior_registers) if
`have_ptrace_getregs' isn't set.
