Returned integer vector mode costs of emulated modes in
ix86_multiplication_cost are wrong and do not reflect generated
instruction sequences.  Rewrite handling of different integer vector
modes and different target ABIs to return real instruction
counts in order to calculate better costs of various emulated modes.

gcc/ChangeLog:

    * config/i386/i386.cc (ix86_multiplication_cost): Correct
    calculation of integer vector mode costs to reflect generated
    instruction sequences of different integer vector modes and
    different target ABIs.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Uros.