A new bug() and BUG_if_bug() API is introduced to make it easier to
uniformly log "detect multiple bugs and abort in the end" pattern.
* ab/bug-if-bug:
cache-tree.c: use bug() and BUG_if_bug()
receive-pack: use bug() and BUG_if_bug()
parse-options.c: use optbug() instead of BUG() "opts" check
parse-options.c: use new bug() API for optbug()
usage.c: add a non-fatal bug() function to go with BUG()
common-main.c: move non-trace2 exit() behavior out of trace2.c
Junio C Hamano