o removed -O3 from mingw debug builds (so the issues below are reproduced on mingw)

o gnu compiler for windows doesnt support well dll exporting individual functions from a class
in debug builds so I switched to exporting the entire interface class in several places
o fixed several places in ca lib where include of epicsTimer.h wasnt properly ifdef'd so
that it is imported by ca header files
--- these issues were already fixed on cvs main trunk ---

src/ca/bhe.cpp

@@ -360,6 +360,6 @@ void bheFreeStore::release ( void * pCadaver )
     freeList.release ( pCadaver );
 }
 
-epicsShareFunc bheMemoryManager::~bheMemoryManager () {}
+bheMemoryManager::~bheMemoryManager () {}