Export symbols as it's done by xf86-input-evdev.

Based on the suggestion by Andrew de los Reyes.
diff --git a/driver/multitouch.c b/driver/multitouch.c
index 99f1484..c7554a6 100644
--- a/driver/multitouch.c
+++ b/driver/multitouch.c
@@ -356,7 +356,7 @@
 	xf86DeleteInput(local, 0);
 }
 
-static InputDriverRec MULTITOUCH = {
+_X_EXPORT InputDriverRec MULTITOUCH = {
 	1,
 	"multitouch",
 	NULL,
@@ -385,4 +385,4 @@
 	return module;
 }
 
-XF86ModuleData multitouchModuleData = {&VERSION, &setup, NULL };
+_X_EXPORT XF86ModuleData multitouchModuleData = {&VERSION, &setup, NULL };