* changed error to warning for unknown build system

dglOpenGLES.pas

@@ -77,7 +77,10 @@ const
   LIBNAME_EGL      = 'libEGL.so';
 
 {$ELSE}
-  {$ERROR 'unknown/unsupported system'}
+const
+  LIBNAME_OPENGLES = '';
+  LIBNAME_EGL      = '';
+  {$WARNING 'unknown/unsupported system'}
 
 {$ENDIF}
 
@@ -4951,6 +4954,7 @@ var
 
 function dglLoadLibrary(const name: PChar): Pointer;
 begin
+  result := nil;
   {$IFDEF DGL_LINUX}
   result := dlopen(name, RTLD_LAZY);
   {$ENDIF}