Data gatherer optimizations

[ampotos]

There is some idea to optimize the data gatherer

• Output buffering
• Inline some of the instrumentations if possible

The output buffering is mainly for the Json ouput (because the console output may disappear soon).
For the inlining of the instrumentations this may require some refactoring or may not be possible. Some research are needed on that.

[ampotos]

Output buffering done in c30affa

[ampotos]

The buffering have an issue on my setup when analizing xterm.
It look like a part of the json data is not wirtten.
The same test work well on a test vm.
Buffering is disable until a fix is pushed.

[ampotos]

The buffering is reactivated but the bug is still present (the old verison of the maccro using dr_fprintf directly is commented to allow quick fix if needed).