bugfix: run go compiler from package directory

The compiler only works correctly if passed an import path or run from
the package directory, the latter of which is the path of least
resistance.

syntax_checkers/go/go.vim

@@ -13,5 +13,19 @@ function! SyntaxCheckers_go_GetLocList()
     let makeprg = 'go build -o /dev/null'
     let errorformat = '%f:%l:%c:%m,%E%f:%l:%m,%C%m,%-G#%.%#'
 
-    return SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })
+    " The go compiler needs to either be run with an import path as an
+    " argument or directly from the package directory. Since figuring out
+    " the poper import path is fickle, just pushd/popd to the package.
+    let popd = getcwd()
+    let pushd = expand('%:p:h')
+    "
+    " pushd
+    exec 'lcd ' . fnameescape(pushd)
+
+    let errors = SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })
+
+    " popd
+    exec 'lcd ' . fnameescape(popd)
+
+    return errors
 endfunction