feat: add lab-rv32i-c-uart card

tests/check_elf.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
+prefix="${RISCV_PREFIX:-riscv64-unknown-elf-}"
+
+make -C "$root" -s tasks
+for elf in "$root"/build/task*/prog.elf; do
+    "$prefix"readelf -h "$elf" | grep -F 'RISC-V' >/dev/null
+    "$prefix"nm -a "$elf" | grep -E ' task0[1-3]_debug_checkpoint$' >/dev/null
+done
+"$prefix"nm -a "$root/build/task02_uart_rx_interrupt/prog.elf" | \
+    grep -E ' task02_uart_handler$' >/dev/null
+"$prefix"nm -a "$root/build/task03_uart_mailbox/prog.elf" | \
+    grep -E ' task03_uart_handler$' >/dev/null
+printf 'PASS: RV32I ELF symbols and handlers\n'