i386: Adjust emulated integer vector mode shift costs

i386: Adjust emulated integer vector mode shift costs

Returned integer vector mode costs of emulated instructions in
ix86_shift_rotate_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 calcuate better costs of various emulated modes.

Also add the cost of a memory read, when the instruction in the
sequence reads memory.

gcc/ChangeLog:

	* config/i386/i386.cc (ix86_shift_rotate_cost): Correct
	calcuation of integer vector mode costs to reflect generated
	instruction sequences of different integer vector modes and
	different target ABIs.  Remove "speed" function argument.
	(ix86_rtx_costs): Update call for removed function argument.
	(ix86_vector_costs::add_stmt_cost): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/sse2-shiftqihi-constant-1.c: Remove XFAILs.