build/clean/crossgcc: better code style

Signed-off-by: Leah Rowe <leah@libreboot.org>

resources/scripts/build/clean/crossgcc

@@ -2,7 +2,7 @@
 
 #  helper script: clean the crossgcc builds
 #
-#	Copyright (C) 2014, 2015, 2016, 2020 Leah Rowe <info@minifree.org>
+#	Copyright (C) 2014-2016, 2020, 2023 Leah Rowe <info@minifree.org>
 #	Copyright (C) 2015 Klemens Nanni <contact@autoboot.org>
 #
 #	This program is free software: you can redistribute it and/or modify
@@ -19,26 +19,28 @@
 #	along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-# This script assumes that the current working directory is the root
-
 [ "x${DEBUG+set}" = 'xset' ] && set -v
 set -u -e
 
-# clean coreboot utilities (dependencies for 'build'):
+main()
+{
+	printf "Cleaning crossgcc builds in all coreboot archives\n"
 
-printf "Cleaning crossgcc builds in all coreboot archives\n"
+	[ ! -d "coreboot/" ] && exit 0
 
-[ ! -d "coreboot/" ] && exit 0
-
-# clean coreboot and crossgcc (source archives preserved)
-for board in coreboot/*; do
-    if [ "${board##*/}" = "coreboot" ]; then
+	for board in coreboot/*; do
+		[ "${board##*/}" = "coreboot" ] && \
 			continue
-    fi
-    if [ ! -d "${board}" ]; then
+		[ ! -d "${board}" ] && \
 			continue
-    fi
-    make -C "${board}/" crossgcc-clean
-done
+		make -C "${board}/" crossgcc-clean || err "make-clean"
+	done
+}
 
-printf "\n\n"
+err()
+{
+	printf "%s: %s\n" $0 $1
+	exit 1
+}
+
+main $@