MinGW build fixes for various applications

[Jon TURNEY]

MinGW build fixes for some applications which are relatively simple to fix.

xauth:

Jon TURNEY (1):
      Include Xwinsock.h rather than sys/socket.h on WIN32

xdpyinfo:

Jon TURNEY (1):
      Include Xwindows.h on WIN32 to avoid type clashes

xkbcomp:

Ryan Pavlik (1):
      Include Xwindows.h rather than windows.h

xmodmap:

Jon TURNEY (1):
      Include X11/Xwindows.h on WIN32

xrdb:

Jon TURNEY (1):
      Fix build with WIN32 defined, but PATHETICCPP not defined

xset:

Jon TURNEY (1):
      Remove unneeded include of windows.h on WIN32