Commit ec360d7a

 made it work for ELF
platforms, Apple platforms and for MSVC, but we apparently forgot it for
MinGW. This patch corrects that mistake.

We won't have the PE-COFF section parser until 5.5, but this will at
least making Qt 5.4-built plugins work on the faster case.

Change-Id: I51b06837dc321eaa4724c9598293cf85570f67fc
Reviewed-by: Lars Knoll <lars.knoll@digia.com>