RISC-V: Adapt live-1.c testcase

Commited.

Fix failures:

FAIL: gcc.target/riscv/rvv/autovec/partial/live-1.c scan-tree-dump-times optimized ".VEC_EXTRACT" 10
FAIL: gcc.target/riscv/rvv/autovec/partial/live-1.c scan-tree-dump-times optimized ".VEC_EXTRACT" 10

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/partial/live-1.c: Adapt test.