Full Octave+GUI+JIT build enabled on Mavericks

Tests for other versions of Mac OSX would be prudent.
* Patches libinterp/corefcn/jit-typeinfo.{cc,h} to enable JIT compilation. (This patch has already been accepted into the dev tree for Octave).
* Patches configure and build-aux/ltmain.sh to enable automatic discovery of the Homebrew Qt frameworks.
* Adds dependencies for qscintilla2 and llvm to enable JIT and GUI.
* Removes autoconf/automake/libtool requirements that are no longer necessary, thanks in part to the patches.