#1515 clangd_client : linux : cpu usage when idle (read)

[Christo]

Unnecessary CPU usage is seen when idle. Similar to #1503. When analysed with perf, is showed select call. With the attached patch, issue is fixed.
Patch changes the delay between select calls- onstead of calling select on stdout and stderror every 10ms separately, do it in 100ms for both together.

[pecan]

Applied rev 13618
thanks Christo