ui: do not build-depend or link with libdrm, it is not needed

Opengl support brings up libdrm. But actually nothing uses this library
or includes any of its headers. Just remove checking for it from configure.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180630165448.30795-1-mjt@msgid.tls.msk.ru
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/configure b/configure
index 65548df..951ff02 100755 (executable)
--- a/configure
+++ b/configure
@@ -3865,7 +3865,7 @@ libs_softmmu="$libs_softmmu $fdt_libs"
 # opengl probe (for sdl2, gtk, milkymist-tmu2)
 
 if test "$opengl" != "no" ; then
-  opengl_pkgs="epoxy libdrm gbm"
+  opengl_pkgs="epoxy gbm"
   if $pkg_config $opengl_pkgs; then
     opengl_cflags="$($pkg_config --cflags $opengl_pkgs)"
     opengl_libs="$($pkg_config --libs $opengl_pkgs)"