RISC-V/testsuite: Add branched cases for equality cond-move operations

RISC-V/testsuite: Add branched cases for equality cond-move operations

Verify, for Ventana and Zicond targets and the equality conditional-move
operations, that if-conversion does *not* trigger at the respective
sufficiently low `-mbranch-cost=' settings that make original branched
code sequences cheaper than their branchless equivalents if-conversion
would emit.

	gcc/testsuite/
	* gcc.target/riscv/movdibeq-ventana.c: New test.
	* gcc.target/riscv/movdibeq-zicond.c: New test.
	* gcc.target/riscv/movdibne-ventana.c: New test.
	* gcc.target/riscv/movdibne-zicond.c: New test.
	* gcc.target/riscv/movsibeq-ventana.c: New test.
	* gcc.target/riscv/movsibeq-zicond.c: New test.
	* gcc.target/riscv/movsibne-ventana.c: New test.
	* gcc.target/riscv/movsibne-zicond.c: New test.