GitLab

Fixed setting of runtime in BrookPlatform() constructor (constructor w/o args):
if 'brt_runtime' env variable not set, then
internal 'runtime' variable was NULL -- this led to a fault when _setBrookRuntime() was called

Commented out static platform variable, which may have caused initialization problems
Some of the Brook tests now succeed on my computer for the first time.

Added  'OPENMM_EXPORT'  to class declaration to deal w/ linking issue associated w/ virtual methods in class
Modified brook/brook-cmake/FindBrook.cmake to only look in $BROOKROOT directory for Brook files