Fix 4 failing llgs-related tests on a stock Ubuntu 14.04 x86_64 system./

This fix addresses a requirement on some Linux kernels that limits
a PTRACER to be an ancestor of the ptraced process.  The fix in this
case is to have the inferior test exe explicitly allow any ptracer
to attach.

This fixes several ptrace-related issues that I did not see on a modified
kernel we used internally on my team.

See http://reviews.llvm.org/D5846 for details.

This fixes these previously failing tests on stock Ubuntu systems:

FAIL: LLDB (suite) :: TestGdbRemoteProcessInfo.py (Linux vagrant 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64)

FAIL: LLDB (suite) :: TestGdbRemoteAttach.py (Linux vagrant 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64)

FAIL: LLDB (suite) :: TestLldbGdbServer.py (Linux vagrant 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64)

FAIL: LLDB (suite) :: TestGdbRemoteKill.py (Linux vagrant 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64)