RISC-V/testsuite: Add RTL pr105314.c testcase variants

Add a pair of RTL tests, for RV64 and RV32 respectively, corresponding
to the existing pr105314.c test.  They have been produced from RTL code
as at the entry of the "ce1" pass for pr105314.c compiled at -O3.

	gcc/testsuite/
	* gcc.target/riscv/pr105314-rtl.c: New file.
	* gcc.target/riscv/pr105314-rtl32.c: New file.