configure: Fix check for iOS for the OpenGL support

There is also an i386 version of iOS, which is for the simulator.
Better use our already existing HAVE_IOS check instead of relying
on the host triplet.

configure.ac

@@ -958,8 +958,12 @@ case $host in
       fi
     fi
     ;;
-  i386*-darwin* | x86_64*-darwin*)
-    dnl Only osx supports cocoa. ios requires EAGL.
+  *-darwin*)
+    if test "x$HAVE_IOS" = "xyes"; then
+      dnl iOS requires EAGL, which we don't support yet
+      AC_MSG_WARN([OpenGL support not ported to iOS yet])
+    else
+      dnl Only osx supports cocoa.
       if test "x$NEED_WGL" = "xyes"; then
         AC_MSG_ERROR([WGL is not available on Mac OS X])
       fi
@@ -997,6 +1001,7 @@ case $host in
           USE_OPENGL=yes
         fi
       fi
+    fi
     ;;
   *-mingw32*)
     if test "x$NEED_GLX" = "xyes"; then