package ffmpeg: disable libnut on i686-pc-mingw32
package qtbase: mingw-w64 fixes
Makefile: allow bypassing check-requirements
package wxwidgets: mingw-w64 fixes
package wget: mingw-w64 cdecl fix
package boost: mingw-w64 intrinsics fix
package qtbase: update patches

-cherry-picked NTLM bugfix
-move _WIN32_WINNT define from patch to qmake -D option to ensure
consistency