fixes #4435 (#9185)

(cherry picked from commit dd65986795)

tests/distinct/t4435.nim

@@ -0,0 +1,21 @@
+discard """
+  output: '''
+A
+A
+'''
+"""
+
+type
+  A[T] = distinct T
+  B[T] = distinct T
+
+proc foo[T](x:A[T]) = echo "A"
+proc foo[T](x:B[T]) = echo "B"
+proc bar(x:A) = echo "A"
+proc bar(x:B) = echo "B"
+
+var
+  a:A[int]
+
+foo(a) # fine
+bar(a) # testdistinct.nim(14, 4) Error: ambiguous call; both testdistinct.bar(x: A) and testdistinct.bar(x: B) match for: (A[system.int])