mips.md (*mul_acc_si): Remove middle alternative and its associated define_split.

mips.md (*mul_acc_si): Remove middle alternative and its associated define_split.

gcc/
	* config/mips/mips.md (*mul_acc_si): Remove middle alternative
	and its associated define_split.  Expose the all-d alternative
	to the register allocator, but mark it with "?".  Mark the first
	alternative with "*?*?".
	(*mul_sub_si): Likewise.
	(*mul_acc_si_r3900): New pattern.

gcc/testsuite/
	* gcc.target/mips/madd-5.c: New test.
	* gcc.target/mips/madd-6.c: Likewise.
	* gcc.target/mips/madd-7.c: Likewise.
	* gcc.target/mips/madd-8.c: Likewise.
	* gcc.target/mips/msub-5.c: Likewise.
	* gcc.target/mips/msub-6.c: Likewise.
	* gcc.target/mips/msub-7.c: Likewise.
	* gcc.target/mips/msub-8.c: Likewise.

From-SVN: r141954