packages qt qtbase: install pkgconfig files in standard location
disable stl for wxWidgets as it seems to be very problematic:

http://www.wxwidgets.org/docs/faqgen.htm#stl
package pthreads-w32: remove patch - DPTW32_STATIC_LIB is define with GC-static target
Revert "package pthreads-w32: remove patch - DPTW32_STATIC_LIB is define with GC-static target"

This reverts commit 71abd6e106a2a3c95202e6e18fc3f47ffeedd7ae.
update package x264
update package curl
update package libpng
package jpeg: fix missing stdio.h for FILE
update package libmng
package qtimageformats: libmng 2 compatibility
package qt: libmng 2 compatibility
package poppler: use lcms 2

Now that Qt uses libmng 2 which uses lcms 2, we should too.
package poppler: fix building poppler Qt 4 libraries

Poppler doesn't use qmake, so we resort to fixing the PATH so moc
can be found by the configure script.
package graphicsmagick: use lcms 2
package sfml: add *.pc file and use for test program
update package gnutls
new package libusb1

This is a package for the libusb-1.0 shared library (MXE package name
"libusb1") used by various projects. It is not to be confused with the
older libusb-0.1 library (MXE package name "libusb") which is a
completely different library with different API. Both libs are in
wide-spread use and can be installed in parallel.
mxe-activate: get targets from Makefile
mxe-activate: clear env vars on make invocation
mxe-activate: unset env vars for interactive use