compiler: fix import of indirectly imported type alias

We were looking for the " = " before the optional package name that
appears for an indirect reference, but the exporter was putting it
after.

Test is https://golang.org/cl/70290.

Change-Id: I9cb11f166418fa593aa1328cd9a1c57dfb5c2286
Reviewed-on: https://go-review.googlesource.com/70330
Reviewed-by: Than McIntosh <thanm@google.com>
1 file changed