fixes both goto_definition and goto_type_definition.
before, when running goto between some non-trivia token and an
identifier, goto would be attempted for the non-trivia token.
but this does not make sense for e.g. L_PAREN or COLONCOLON only for
IDENTs. now only IDENTs will be searched for in goto actions.
SourceAnalyzer didn't work properly within expression macro expansions because
it didn't find the enclosing function. Fix this by going up the expansion chain
to find ancestors. This makes the test work, but apparently in real usage it's
still not working.
