fixes #23949; cannot return lent expression from conditionals like case (#25190)

fixes #23949

It can also allow  `endsInNoReturn` in branches later

tests/lent/tlents.nim

@@ -0,0 +1,25 @@
+discard """
+  targets: "c cpp"
+"""
+
+type A = object
+  field: int
+
+proc x(a: A): lent int =
+  result = case true
+    of true:
+      a.field
+    of false:
+      a.field
+
+proc y(a: A): lent int =
+  result = if true:
+      a.field
+    else:
+      a.field
+
+block:
+  var a = A(field: 1)
+  doAssert x(a) == 1
+  doAssert y(a) == 1
+