[PATCH] [Sanitizer] Get the Linux ptrace test working on PowerPC64

[Kostya Serebryany]

- please upload patcehs with full context (easier with 'arc')
- please don't rename the file to .c, instead cast integer to the enum type and file a bug against the linux headers and/or clang -- this warning must not be there.

http://reviews.llvm.org/D6108