XlibInt.c: In function ‘_XIOError’:
XlibInt.c:3750:1: warning: ‘noreturn’ function does return [enabled by default]
 }

After fixing the above a new warning came up, which is also fixed now:

XlibInt.c: In function ‘_XIOError’:
XlibInt.c:3750:1: warning: control reaches end of non-void function [-Wreturn-type]
 }