MJPEG Tools Svn

https://sourceforge.net/tracker/index.php?func=detail&aid=1215231&group_id=5776&atid=105776

Problem of undefined symbol (next_larger_quant) is caused by utils/altived/
libaltivec referencing encoder routines that are in libmpeg2encpp! Can't do
that because libmpeg2encpp hasn't been built yet!!

Attempted solution is to move mpeg2enc immediately after utils/ in the
top level Makefile.am. Then move mjpeg_simd_helper into lavtools/. THEN
add 'if HAVE_ALTIVEC' to all the other Makefile.am files and add libmpeg2encpp
to the list of library dependencies.

Klug? Sure - feel free to fix it differently :)