bootstrap: fix shellcheck warnings

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I86ef079c9632e5563a1a56d6a2e23aad59ecbc57
diff --git a/bootstrap.sh b/bootstrap.sh
index 1bca169..d5b6ea4 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -13,11 +13,12 @@
     clean)
         test -f Makefile && make maintainer-clean
         for file in ${AUTOCONF_FILES}; do
-            find -name "$file" | xargs -r rm -rf
+            find . -name "$file" -print0 | xargs -0 -r rm -rf
         done
         exit 0
         ;;
 esac
 
 autoreconf -vfi
+# shellcheck disable=SC2016
 echo 'Run "./configure ${CONFIGURE_FLAGS} && make"'