Replace realpath command with python equivalent

Most systems don't have realpath installed, so changed the build
script to use python instead.
Remove the "-j" option to make

Removed the "-j" option to make when building Bro, because it
causes my ubuntu 12.04.2 machine to lock up.
Remove unused Makefile variable

Removed an unused Makefile variable that was introduced
in commit 2419328fa0f78398c77a3e754b222d305fa83085.
Minor cleanup of the build script

Reorganized a few things in the build script.  Renamed a variable for
clarity.  Removed an unused variable.  Removed a redundant mkdir.
Improved an error message.  Now that BROCTL_TEST directory is no
longer hard-coded to be in /tmp, there's not really any reason for
a user to specify their own location.
Remove "make quick" from the README

When the "quick" target was removed from the Makefile, the documentation
of it was not removed.
Update baselines for recent changes to crash-diag
Fix a canonifier script

A couple of tests would fail (due to a difference in the crash-diag output)
if gdb was not installed, so the diff-diag-output canonifier script has
been fixed to prevent this.
Merge remote-tracking branch 'origin/topic/dnthayer/broctl-testing-fixes'

Closes #1028.

* origin/topic/dnthayer/broctl-testing-fixes:
  Fix a canonifier script
  Update baselines for recent changes to crash-diag
  Remove "make quick" from the README
  Minor cleanup of the build script
  Remove unused Makefile variable
  Remove the "-j" option to make
  Replace realpath command with python equivalent