In addition to fixing getContainingDeclaration, change origin of
multifile facades to FILE_CLASS since the corresponding class descriptor
should also be skipped when computing containing declaration. This fixes
the problem with internal function calls in -Xmultifile-parts-inherit
mode (previously we incorrectly mangled the function name in
MethodSignatureMapper), and also fixes coroutine intrinsic calls when
compiling kotlin-stdlib with JVM IR. In the latter case, all intrinsics
(such as isBuiltInSuspendCoroutineUninterceptedOrReturn) are present in
sources, and were previously not detected as intrinsics by the code in
`generateInlineIntrinsic` because the FQ name didn't match: it had an
additional component for the file class name.
