rcu: Remove "extern" from function declaration in include/linux/rcupdate.h
rcu: Remove "extern" from function declaration in include/linux/rcupdate.h

Because functions have the extern storage class specifier by default,
this keyword can be removed. It is redundant to use it explicitly.

Signed-off-by: Iulia Manda <80e86c6595d2e20a4677fac041731491bdb892c6@gmail.com>
Signed-off-by: Paul E. McKenney <1e0ce936bb9b355d257bf5790d2513c3f28be22b@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <c028c213ed5efcf30c3f4fc7361dbde0c893c5b7@joshtriplett.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs