Take the full step and wrap all our mutex operations in proper C functions

Take the full step and wrap all our mutex operations in proper C functions
instead of increasingly unwieldy macros.

Amongst other things, this will make it much easier to do lock
profiling, contest statistics, asserts etc.

This commit is largely mechanically generated and should not result in
any changed functionality.

Locks retain the "mtx" monicker, as a reminder that they are mutexes.

No performance impact expected.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@3381 d4fa192b-c00b-0410-8231-f00ffab90ce4