Make sure that the PTRACE_... symbols are available for ppc/plt.c.

On a Fedora 12 x86_64 build/host box, this file was complaining about
PTRACE_PEEKTEXT being undefined. Adding in the "ptrace.h" include
fixed it.

Signed-off-by: Anthony Foiani <anthony.foiani@gmail.com>

# Alpha specific configuration file

config ARCH_alpha

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_USE_MMU

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    help

      The Alpha architecture.