gnu: antlr3: Make antlr3-3.3 public.

This is done in preparation of adding Linphone, which transitively requires
antlr3-3.3 through its belle-sip dependency.

* gnu/packages/java.scm (antlr3): Make antlr3-3.3 public.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

gnu/packages/java.scm

@@ -7160,7 +7160,7 @@ tree walking, and translation.")
     (inputs
      `(("junit" ,java-junit)))))
 
-(define antlr3-3.3
+(define-public antlr3-3.3
   (package
     (inherit antlr3)
     (name "antlr3")