As submitted upstream in a review, avoid using undefined behavior in

As submitted upstream in a review, avoid using undefined behavior in
llvm's LinkAllPasses.h.  This caused some of the calls not to be
emitted, if the optimization level was -O2 or higher.

Conversely, if you used -O1 or lower, calls to e.g.  RunningOnValgrind()
would be emitted, leading to link failures, because we did not include
Valgrind.cpp into libllvmsupport.  Therefore, add it unconditionally.

Noticed by:	ian