Fix recently-introduced profile parsing bugs

Fix recently-introduced profile parsing bugs

When parsing a "}", do not ascend to the parent node if we are still
within a discarded section after decrementing group_level, as we did
not descend into a child node at the beginning of the subsection.
(Discovered by OSS-Fuzz.)

Also adjust the level check to take into account the shifted meaning
of state->group_level, so that we properly reject a "}" within a
top-level section.

Both bugs were introduced in commit
f951625e6bd3ff44f1056958b56e35a1a043e362.