add a text queue to be able to ignore unexpected gdb output; handle r…

[johnlvogt]

The previous version just read output from gdb from a stream, but this proved brittle because if gdb produced extra output, gdb.py would return the result from the previous command for every ensuing command. This version reads the gdb output on a separate thread which keeps it from blocking if the gdb doesn't produce output when expected, and also allows each operation to flush any unprocessed output from the previous command.

There is also a section of changes related to rocgdb specific changes in the format for thread info.

[codecov-commenter]

Codecov Report

Merging #32 (17c82e8) into develop (445537f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop      #32   +/-   ##
========================================
  Coverage    44.50%   44.50%           
========================================
  Files           10       10           
  Lines         6465     6465           
========================================
  Hits          2877     2877           
  Misses        3588     3588           

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[coveralls]

Pull Request Test Coverage Report for Build 642

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 32.468%

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Totals
Change from base Build 639:	0.0%
Covered Lines:	3378
Relevant Lines:	10404

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💛 - Coveralls