riscv: Fix incorrect gnu property alignment on rv32

riscv: Fix incorrect gnu property alignment on rv32

Codegen is incorrectly emitting a ".p2align 3" that coerces the
alignment of the .note.gnu.property section from 4 to 8 on rv32.

2025-04-11  Jesse Huang  <jesse.huang@sifive.com>

gcc/ChangeLog

	* config/riscv/riscv.cc (riscv_file_end): Fix .p2align value.

gcc/testsuite/ChangeLog

	* gcc.target/riscv/gnu-property-align-rv32.c: New file.
	* gcc.target/riscv/gnu-property-align-rv64.c: New file.