SI-9326 Fix regression with existentials in parent types

The typechecker rewrites `p.foo` to `p.<package>.foo` if `foo`
must come from a package object. This logic was overhauled in
51745c06f3, but this caused a regression.

I reverted to the predecessor of that commit to see how things
worked before. The lookup of the name `X` bound to the existential
quantifier, but incorrectly included the prefix `test.type` in the
result of the lookup. However, the subsequent call to
`isInPackageObject` (from `makeAccessible`) returned false, so
we didn't try to rewrite `X` to `test.<package>.X`.

This commit makes a minimal fix that makes `isInPackageObject`
return false for existentials.

1 files changed, 6 insertions, 0 deletions

diff --git a/test/files/pos/t9326a.scala b/test/files/pos/t9326a.scala
new file mode 100644
index 0000000000..aefc735585
--- /dev/null
+++ b/test/files/pos/t9326a.scala
@@ -0,0 +1,6 @@
+package p
+
+trait M[A]
+
+class C extends M[Tuple1[X] forSome { type X }]
+