ibrcommon: Code clean-up of __compat_select()
ibrcommon: Use CLOCK_BOOTTIME instead of CLOCK_MONOTONIC

Use CLOCK_BOOTTIME for monotonic clock references because in contrast to
CLOCK_MONOTONIC it includes seconds spend in suspend / deep sleep.
ibrcommon: Remove monotonic clock methods for relative time-stamps
ibrcommon: Code-style fixes
Merge pull request #61 from morgenroth/Improve-monotonic-time-code

Improve monotonic time functions
ibrcommon: Use CLOCK_BOOTTIME only if defined
Merge pull request #62 from morgenroth/Use-boottime-clock-only-if-defined

ibrcommon: Use CLOCK_BOOTTIME only if defined