This patch fixes build of AAC encoder optimized for mips that was broken due
 to some changes in generic code that were not propagated to the optimized code.

Also, some functions in the optimized code are basically duplicate of functions
 from generic code. Since they do not bring enough improvement to the optimized
 code to justify their existence, they are removed (which improves
 maintainability of the optimized code).

Optimizations disabled in 97437bd1 are enabled again.
Signed-off-by: Nedeljko Babic <nedeljko.babic@imgtec.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>