Detect SW breakpoints in Cell/B.E. combined debugging

Detect SW breakpoints in Cell/B.E. combined debugging

The Linux target and gdbserver now check the siginfo si_code
reported on a SIGTRAP to detect whether the trap indicates
a software breakpoint was hit.

Unfortunately, on Cell/B.E., the kernel uses an si_code value
of TRAP_BRKPT when a SW breakpoint was hit in PowerPC code,
but a si_code value of SI_KERNEL when a SW breakpoint was
hit in SPU code.

This patch updates Linux target and gdbserver to accept both
si_code values to indicate SW breakpoint on PowerPC.

ChangeLog:

	* nat/linux-ptrace.h (GDB_ARCH_TRAP_BRKPT): Replace by ...
	(GDB_ARCH_IS_TRAP_BRKPT): ... this.  Add __powerpc__ case.
	* linux-nat.c (check_stopped_by_breakpoint): Use
	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.

gdbserver/ChangeLog:

	* linux-low.c (check_stopped_by_breakpoint): Use
	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.