[PATCH v3] perf: Split out arch specific code & improve PowerPC perf probe support

[Ian Munsie]

These patches add the required mappings to use perf probe on PowerPC.

Part 1 of the patch series moves the arch dependent x86 32 and 64 bit DWARF
register number mappings out into a separate arch directory and adds the
necessary Makefile foo to use it.

Part 2 of the patch series adds the PowerPC mappings -
Functionality wise it requires the patch titled "powerpc: Add kprobe-based
event tracer" from the powerpc-next tree to provide the
HAVE_REGS_AND_STACK_ACCESS_API required for CONFIG_KPROBE_EVENT. The code will
still compile cleanly without it and will fail gracefully at runtime on the
missing CONFIG_KPROBE_EVENT support as before as well as printing a warning
message during compilation.


Changes since v2: From Masami Hiramatsu's feedback DWARF support is disabled
altogether if the architecture specific Makefile does not define
PERF_HAVE_DWARF_REGS - ie, DWARF register mappings are missing for the
architecture. A message indicating this is printed out during compilation.