Modifying pointer_deref_comparison.patch as follows works for me.
--- a/debian/patches/pointer_deref_comparison.patch
+++ b/debian/patches/pointer_deref_comparison.patch
@@ -5,7 +5,7 @@
}
if (alvec) {
- if ((alvecp = *alvec) != '\0') {
-+ if (*(alvecp = *alvec) != '\0') {
++ if ((alvecp = *alvec) != NULL) {
alvec++;
goto top;
}
@@ -14,7 +14,7 @@
reset();
}
- if ((evalp = *evalvec) != '\0') {
-+ if (*(evalp = *evalvec) != '\0') {
++ if ((evalp = *evalvec) != NULL) {
evalvec++;
goto top;
}

