All of these changes avoid using the same name for two local variables
within a same function. None of them are actual bugs as far as I can tell,
but any of them could be confusing to the casual reader.
The one in lib/ovsdb-idl.c is particularly brilliant: inner and outer
loops both using (different) variables named 'i'.
Found with GCC -Wshadow.
Most of the timekeeping needs of OVS are simply to measure intervals,
which means that it is sensitive to changes in the clock. This commit
replaces the existing clocks with monotonic timers. An additional set
of wall clock timers are added and used in locations that need absolute
time.
Bug #1858
