configure: loosen --with-platforms heuristics

Remove the enable-egl pre-requirement. Platform selection does not
depend on EGL.

Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
diff --git a/configure.ac b/configure.ac
index 2c93000..de42210 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1643,14 +1643,10 @@
     [with_egl_platforms=auto])
 
 if test "x$with_egl_platforms" = xauto; then
-    if test "x$enable_egl" = xyes; then
-        if test "x$enable_gbm" = xyes; then
-           with_egl_platforms="x11,drm"
-        else
-           with_egl_platforms="x11"
-        fi
+    if test "x$enable_gbm" = xyes; then
+        with_egl_platforms="x11,drm"
     else
-        with_egl_platforms=""
+        with_egl_platforms="x11"
     fi
 else
     AC_MSG_WARN([--with-egl-platforms is deprecated. Use --with-platforms instead.])