TBR: i#2147: fix drmemtrace reachability failure with -prof_pcs

Commit log for first patchset:
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i#2147: fix drmemtrace reachability failure with -prof_pcs

For -prof_pcs drmemtrace's jecxz won't reach over an out-of-line clean
call.  We use a brute-force quick solution of checking for the option and
using a jecxz;jmp;jmp sequence when it's on.

Fixes #2147
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[bruening, 2017-01-26 03:48:33]

Committed as
https://github.com/DynamoRIO/dynamorio/commit/16f386358c2c1000005590d2fbc1ba5...

Final commit log: 
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i#2147: fix drmemtrace reachability failure with -prof_pcs

For -prof_pcs drmemtrace's jecxz won't reach over an out-of-line clean
call.  We use a brute-force quick solution of checking for the option and
using a jecxz;jmp;jmp sequence when it's on.

Fixes #2147

Review-URL: https://codereview.appspot.com/316170043
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