Replace clang-format with uncrustify

LLVM/clang is not used for any compilation due to it not supporting the
8-bit architectures we use (MCS-51, AVR). This means we are effectively
installing 250+ MiB of dependencies for a C formatting tool.

Replace it with uncrustify, which uses only ~600 KiB of space and has
more granular control of formatting (800+ options).

Signed-off-by: Tim Crawford <tcrawford@system76.com>

scripts/lint/02-uncrustify.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-3.0-only
+
+# Check if any C files or headers need to be formatted.
+
+# shellcheck disable=SC1091
+
+LINT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &> /dev/null && pwd)
+. "$LINT_DIR/util.sh"
+
+echo -n "Checking C style..."
+
+if ! command -v uncrustify > /dev/null; then
+    skipped "uncrustify not found"
+    exit 0
+fi
+
+needs_formatting=()
+
+for file in $(git ls-files '*.c' '*.h'); do
+    if ! uncrustify -c .uncrustify.cfg -q --check "$file" >/dev/null 2>&1; then
+        needs_formatting+=("$file")
+    fi
+done
+
+if [[ "${#needs_formatting[@]}" != "0" ]]; then
+    failed
+
+    for file in "${needs_formatting[@]}"; do
+        echo "- $file"
+    done
+
+    exit 1
+fi
+
+passed