build: check for dlopen() when we build the ecore_evas drm module

We use it to check for libglapi.so.0

Original patch by aerodynamik

ref T2953

configure.ac

@@ -4342,6 +4342,9 @@ EFL_EVAL_PKGS([ECORE_EVAS])
 ### Checks for linker characteristics
 
 ### Checks for library functions
+if test "x${want_gl_drm}" = "xyes" ; then
+   EFL_CHECK_FUNCS([ECORE_EVAS], [dlopen])
+fi
 
 EFL_LIB_END([Ecore_Evas])
 #### End of Ecore_Evas