qmlplugindump: Fix platform plugin specification.

Fix warning:
Project WARNING: CONFIG+=qpa_minimal_plugin is deprecated. Use QTPLUGIN.platforms=qminimal instead.

Change-Id: I33330bdbe7639de777b4f0fedd4ecadd184733bf
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Don't use a variable called 'interface'

MSVC has #define interface struct, resulting in a nonsensical error from
the compiler about "struct: missing tag name" in a line that doesn't say
"struct".

Change-Id: I1ca703fd7920052e9d0bdf9a6936df77597ff022
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Fix copy and paste error

Fix error 13 identified by static analysis from
http://www.viva64.com/en/b/0251/

This is in line with qtdeclarative.

Change-Id: I3d3879bb93f9ae5bdcdd583645b1657f55140fdf
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>