Extended Description

Consider the following code, and assume that FOO is not defined:

#ifdef FOO
#elfidef BAR
#endif

In this case, we do not issue any diagnostic about the typo where #elifdef is misspelled as #elfidef because it appears within a preprocessor branch that is discarded.

When scanning for the end of the discarded block, we should consider typo corrections for non-directives to help catch this sort of mistake.