This commit uses the new flag "enumerator" to support comma-delimited
lists of flags for both the btl and btl atomic flags. After this
commit is is valid to specify something like -mca btl_foo_flags
self,put,get,in-place. All non-deprecated flags are supported by the
enumerator.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>