virkeyfile: define IS_ASCII instead c_isascii from gnulib
virkeyfile: define IS_ASCII instead c_isascii from gnulib

GLib doesn't provide alternative to c_isascii and this is the only usage
of that macro so define a replacement ourselves.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Cole Robinson <7cd45ff6ad1fb7cf556a02797d774247851499f8@redhat.com>

libvirt/libvirt,olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,fabianfreyer/libvirt,libvirt/libvirt,nertpinx/libvirt,libvirt/libvirt,crobinso/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,libvirt/libvirt,nertpinx/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jardasgit/libvirt,jfehlig/libvirt,jardasgit/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,olafhering/libvirt,zippy2/libvirt,jardasgit/libvirt,zippy2/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,crobinso/libvirt,jardasgit/libvirt,zippy2/libvirt,olafhering/libvirt,zippy2/libvirt,fabianfreyer/libvirt,nertpinx/libvirt