libXxf86misc is the client-side code of an X extension that has not been
supported by the Xserver in more than 10 years. Since xscreensaver's dependency
on it is automagic, we have to patch configure.in to safely remove it.

https://bugs.gentoo.org/720158

diff -ruN xscreensaver.orig/configure.ac xscreensaver/configure.ac
--- xscreensaver.orig/configure.ac	2020-05-02 18:09:23.169324761 -0700
+++ xscreensaver/configure.ac	2020-05-02 18:09:52.578233240 -0700
@@ -104,12 +104,6 @@
 	    (It's available if the file /usr/include/X11/extensions/XInput.h
 	    exists.)])
 
-AH_TEMPLATE([HAVE_XF86MISCSETGRABKEYSSTATE],
-	    [Define this if you have the XF86MiscSetGrabKeysState function
-	    (which allows the Ctrl-Alt-KP_star and Ctrl-Alt-KP_slash key
-	    sequences to be temporarily disabled.  Sadly, it doesn't affect
-	    Ctrl-Alt-BS or Ctrl-Alt-F1.)])
-
 AH_TEMPLATE([HAVE_RANDR],
 	    [Define this if you have the Resize and Rotate extension.
 	    This is standard on sufficiently-recent XFree86 systems, and
@@ -1888,25 +1882,6 @@
 fi
 
 
-###############################################################################
-#
-#       Check for XF86MiscSetGrabKeysState (but only bother if we are already
-#	using other XF86 stuff.)
-#
-###############################################################################
-
-have_xf86miscsetgrabkeysstate=no
-if test "$have_xf86gamma" = yes -o "$have_xf86vmode" = yes; then
-  AC_CHECK_X_LIB(Xxf86misc, XF86MiscSetGrabKeysState,
-                [have_xf86miscsetgrabkeysstate=yes],
-                [true], -lXext -lX11)
-  if test "$have_xf86miscsetgrabkeysstate" = yes ; then
-    SAVER_LIBS="$SAVER_LIBS -lXxf86misc"
-    AC_DEFINE(HAVE_XF86MISCSETGRABKEYSSTATE)
-  fi
-fi
-
-
 ###############################################################################
 #
 #       Check for HP XHPDisableReset and XHPEnableReset.