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; }