Input: Mac button emulation - allow compiling as a module

Not all systems require Mac-style button emulation, however distributions
enable it by default so it is readily available. Allow compiling it as a
module so it can be loaded only on systems that actually require it.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/macintosh/Kconfig

@@ -171,9 +171,8 @@ config INPUT_ADBHID
 	  If unsure, say Y.
 
 config MAC_EMUMOUSEBTN
-	bool "Support for mouse button 2+3 emulation"
-	depends on SYSCTL
-	select INPUT
+	tristate "Support for mouse button 2+3 emulation"
+	depends on SYSCTL && INPUT
 	help
 	  This provides generic support for emulating the 2nd and 3rd mouse
 	  button with keypresses.  If you say Y here, the emulation is still
@@ -185,6 +184,9 @@ config MAC_EMUMOUSEBTN
 
 	  If you have an Apple machine with a 1-button mouse, say Y here.
 
+	  To compile this driver as a module, choose M here: the
+	  module will be called mac_hid.
+
 config THERM_WINDTUNNEL
 	tristate "Support for thermal management on Windtunnel G4s"
 	depends on I2C && I2C_POWERMAC && PPC_PMAC && !PPC_PMAC64