fix: Safer .dd generation

Author: krlmlr

src/deps.mk

@@ -5,4 +5,4 @@ include $(GLUE_CPP_SOURCES:.o=.dd)
 # Include only local dependencies for smaller footprint
 # Add trailing backslash and sort
 %.dd: %.d
-	sed -r 's/([^ ]) ([^ \\])/\1 \\\n  \2/g' $< | sed -r '/^  ([/]|vendor|[.][.])/D;$$s/([^\\])$$/\1 \\/' | { echo "# Generated by deps.mk, do not edit by hand and do not add dependencies to system headers"; read -r header; printf '%s\n' "$$header"; LC_ALL=C sort; } > $@
+	sed -r 's/([^ ]) ([^ \\])/\1 \\\n  \2/g' $< | sed -r '/^ +([/]|vendor|[.][.])/D;$$s/([^\\])$$/\1 \\/' | { echo "# Generated by deps.mk, do not edit by hand and do not add dependencies to system headers"; read -r header; printf '%s\n' "$$header"; LC_ALL=C sort; } > $@