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