The bearermonitor example tries to link against 'Ws2_32' instead of 'ws2_32' which breaks cross-compilation

When cross-compiling Qt on a Linux host using the MinGW toolchain the compilation of the bearermonitor example fails
as it tries to link against 'Ws2_32' instead of 'ws2_32'. As Linux is case sensitive this will result in a compile failure. Attached patch fixes this