TBR: i#1273 use drmgr everywhere: update opcodes to use drmgr

Commit log for first patchset:
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i#1273 use drmgr everywhere: update opcodes to use drmgr

Updates the opcodes sample to use drmgr's insertion event, but look ahead
to insert all the counters at once.  This is the simplest compromise, as
strict analysis vs insertion separation would be inefficient here.
With drreg's latest optimization of keeping aflags in xax, there is no loss
in instrumentation efficiency from this change.
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[bruening, 2017-01-30 06:15:59]

Committed as
https://github.com/DynamoRIO/dynamorio/commit/5f23fd859590280c3c519eca8bbddfa...

Final commit log: 
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i#1273 use drmgr everywhere: update opcodes to use drmgr

Updates the opcodes sample to use drmgr's insertion event, but look ahead
to insert all the counters at once.  This is the simplest compromise, as
strict analysis vs insertion separation would be inefficient here.
With drreg's latest optimization of keeping aflags in xax, there is no loss
in instrumentation efficiency from this change.

Review-URL: https://codereview.appspot.com/318370043
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