If the target files contains `//line` directive and it indicates
a non-go file, the linter is going to handle it as a go file,
which results in failure.
The cause of this issue is that the linters (`Analyzer`s) are using
`pass.Fset.Position()`. This func returns the adjusted position using
`//line` directive.
The example project reported in #998 has `//line` directive that
indicates other non-go file.
According to the description of "Compiler Directives”
(https://golang.org/cmd/compile/#hdr-Compiler_Directives),
line directives is mainly used for reporting original positions to
the generators or something.
On linters of golangci-lint, `pass.Fset.Position()` is used just to
aggregate file names; we don't have to adjust positions.
This changes `Analyzer`s that use `pass.Fset.Position()` to aggregate
file names to use `pass.Fset.PositionFor()` with `adjusted == false`.
Relates: #998
Run all linters per package. It allows unloading package data when it's
processed. It dramatically reduces memory (and CPU because of GC) usage.
Relates: #337
