[PATCH] mutex subsystem, add typecheck_fn(type, function)

add typecheck_fn(type, function) to do type-checking of function
pointers.

Modified-by: Ingo Molnar <mingo@elte.hu>

(made it typeof() based, instead of typedef based.)

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>