compiler: fix parsing of composite literals with omitted pointer types

compiler: fix parsing of composite literals with omitted pointer types

    The frontend could parse omitted pointer typess at the end of the
    type, but not in the middle, so code like []*[][]int{{{1}}} failed.

    Test case is in https://golang.org/cl/123477.

    Fixes golang/go#26340

    Reviewed-on: https://go-review.googlesource.com/123479

From-SVN: r262641