Raise minimum supported Xserver version from 1.4 to 1.18
Recent commits have unconditionally used API's introduced in newer versions:
-
XNFasprintf()
introduced in xorg/xserver@c95c1d33 - xserver-1.10.0 -
XNFcallocarray()
introduced in xorg/xserver@b96dc999 - xserver-1.18.0
cc @metux