https://bugs.gentoo.org/713418
Backport from Xorg: https://gitlab.freedesktop.org/xorg/xserver/-/commit/6634ffc4d26846dcf892f27682f9021f6d9956a9

--- a/nx-X11/programs/Xserver/Xext/xf86bigfont.c
+++ b/nx-X11/programs/Xserver/Xext/xf86bigfont.c
@@ -40,14 +40,7 @@
 
 #include <sys/types.h>
 #ifdef HAS_SHM
-#if defined(linux) && (!defined(__GNU_LIBRARY__) || __GNU_LIBRARY__ < 2)
-/* libc4 does not define __GNU_LIBRARY__, libc5 defines __GNU_LIBRARY__ as 1 */
-/* Linux libc4 and libc5 only (because glibc doesn't include kernel headers):
-   Linux 2.0.x and 2.2.x define SHMLBA as PAGE_SIZE, but forget to define
-   PAGE_SIZE. It is defined in <asm/page.h>. */
-#include <asm/page.h>
 #include <limits.h>
-#endif
 #ifdef SVR4
 #include <sys/sysmacros.h>
 #endif