RISC-V: Use vmv1r.v instead of vmv.v.v for fma output reloads [PR114200].

RISC-V: Use vmv1r.v instead of vmv.v.v for fma output reloads [PR114200].

Three-operand instructions like vmacc are modeled with an implicit
output reload when the output does not match one of the operands.  For
this we use vmv.v.v which is subject to length masking.

In a situation where the current vl is less than the full vlenb
and the fma's result value is used as input for a vector reduction
(which is never length masked) we effectively only reduce vl
elements.  The masked-out elements are relevant for the
reduction, though, leading to a wrong result.

This patch replaces the vmv reloads by full-register reloads.

gcc/ChangeLog:

	PR target/114200
	PR target/114202

	* config/riscv/vector.md: Use vmv[1248]r.v instead of vmv.v.v.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/pr114200.c: New test.
	* gcc.target/riscv/rvv/autovec/pr114202.c: New test.