Merge branch 'kb/perf-trace'

* kb/perf-trace:
api-trace.txt: add trace API documentation
progress: simplify performance measurement by using getnanotime()
wt-status: simplify performance measurement by using getnanotime()
git: add performance tracing for git's main() function to debug scripts
trace: add trace_performance facility to debug performance issues
trace: add high resolution timer function to debug performance issues
trace: add 'file:line' to all trace output
trace: move code around, in preparation to file:line output
trace: add current timestamp to all trace output
trace: disable additional trace output for unit tests
trace: add infrastructure to augment trace output with additional info
sha1_file: change GIT_TRACE_PACK_ACCESS logging to use trace API
Documentation/git.txt: improve documentation of 'GIT_TRACE*' variables
trace: improve trace performance
trace: remove redundant printf format attribute
trace: consistently name the format parameter
trace: move trace declarations from cache.h to new trace.h

diff --cc Documentation/git.txt
Simple merge

diff --cc Makefile
Simple merge

diff --cc builtin/receive-pack.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc commit.h
Simple merge

diff --cc config.mak.uname
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc git.c
Simple merge

diff --cc sha1_file.c
Simple merge

diff --cc t/test-lib.sh
Simple merge

diff --cc wt-status.c
Simple merge