library/unwind: Add support for RISC-V 32-bit

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Author: alistair23

library/unwind/src/libunwind.rs

@@ -57,6 +57,9 @@ pub const unwinder_private_data_size: usize = 2;
 #[cfg(target_arch = "riscv64")]
 pub const unwinder_private_data_size: usize = 2;
 
+#[cfg(target_arch = "riscv32")]
+pub const unwinder_private_data_size: usize = 2;
+
 #[cfg(target_os = "emscripten")]
 pub const unwinder_private_data_size: usize = 20;