Remove libXScrnSaver-devel from BuildRequires

As @ajax pointed out in an internal discussion, SDL2 loads the symbols
for several X11 extensions at runtime (see
SDL2/src/video/x11/SDL2_x11dyn.c). That means we should be able to get
rid of most of those at build time.

For now, let's be conservative and make sure we get rid of at least
libXScrnSaver-devel, as that isn't exposed by Xwayland.

Resolves: https://issues.redhat.com/browse/RHEL-37559

SDL2.spec

@@ -37,7 +37,6 @@ BuildRequires:  libX11-devel
 BuildRequires:  libXi-devel
 BuildRequires:  libXrandr-devel
 BuildRequires:  libXrender-devel
-BuildRequires:  libXScrnSaver-devel
 BuildRequires:  libXinerama-devel
 BuildRequires:  libXcursor-devel
 BuildRequires:  systemd-devel