configure: set up simple clients independently from the others

Namely, simple-client and simple-shm.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
diff --git a/configure.ac b/configure.ac
index 756b125..228b527 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,14 +86,19 @@
   PKG_CHECK_MODULES(WAYLAND_COMPOSITOR, [wayland-client wayland-egl])
 fi
 
+AC_ARG_ENABLE(simple-clients, [  --enable-simple-clients],, enable_simple_clients=yes)
+AM_CONDITIONAL(BUILD_SIMPLE_CLIENTS, test x$enable_simple_clients == xyes)
+if test x$enable_simple_clients == xyes; then
+  AC_DEFINE([BUILD_SIMPLE_CLIENTS], [1], [Build the Wayland simple clients])
+  PKG_CHECK_MODULES(SIMPLE_CLIENT,
+                    [egl >= 7.10 glesv2 wayland-client wayland-egl])
+fi
 
 AC_ARG_ENABLE(clients, [  --enable-clients],, enable_clients=yes)
 AM_CONDITIONAL(BUILD_CLIENTS, test x$enable_clients == xyes)
 if test x$enable_clients == xyes; then
   AC_DEFINE([BUILD_CLIENTS], [1], [Build the Wayland clients])
 
-  PKG_CHECK_MODULES(SIMPLE_CLIENT,
-                    [egl >= 7.10 glesv2 wayland-client wayland-egl])
   PKG_CHECK_MODULES(CLIENT, [wayland-client wayland-egl egl >= 7.10 gl cairo >= 1.10.0 gdk-pixbuf-2.0 glib-2.0 gobject-2.0 xkbcommon])
 
   PKG_CHECK_MODULES(POPPLER, [poppler-glib gdk-2.0 gio-2.0],