[PATCH 0/5] changes to -config.pri for a native win32 build

[Lubomir I. Ivanov]

these are 90% of the required changes that i had to make to
subsurface-configure.pri for subsurface to build with qmake on Win32.

i won't defend these patches much as i'm not much of packaging,
gnu-make or qmake expert, but all of these were important for the
build to work.

in another email i will explain some qmake->Makefile.* output issues
(perhaps bugs) that i'm facing.

[PATCH 1/5] subsurface-configure.pri: pkg-config detection change
[PATCH 2/5] subsurface-configure.pri: enable the libusb detection
[PATCH 3/5] subsurface-configure.pri: add another libxml/libxslt
[PATCH 4/5] subsurface-configure.pri: add a libiconv dependency
[PATCH 5/5] subsurface-configure.pri: add an extra Marble detection