Do not require @targetName for ambiguous inline definitions

[ntnj]

Currently inline methods require @targetName to disambiguate definitions which are same after type erasure. e.g.

class A
class B
class C[T]
extension (c: C[A))
  inline def m() = ???
extension (c: C[B])
  inline def m() = ???  // Fails with "Double definitions" error unless @targetName is added.

Since inline methods are not added to bytecode, this should not require a @TargetNAME annotation.