Merging r277997, r277999 and r278001:

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r277997 | labath | 2016-08-08 05:26:57 -0700 (Mon, 08 Aug 2016) | 3 lines

Remove _isatty from Android.h

it is just #defined to isatty anyway, which lldb already knows how to use.
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r277999 | labath | 2016-08-08 05:40:11 -0700 (Mon, 08 Aug 2016) | 3 lines

Remove SYS_tgkill from Android.h

instead, use __NR_tgkill directly, which seems to be the preferred form in the codebase anyway.
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r278001 | labath | 2016-08-08 06:13:03 -0700 (Mon, 08 Aug 2016) | 5 lines

Clean up linux/Ptrace.h

This removes references to PT_XXX macros from the file, as they were not used anyway. It also
changes the macro used to check for the definition of __ptrace_request, as there are other C
libraries which do not define this type.
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llvm-svn: 278540