A large number of targets were doing a mkdir -p openssl. A parallel make

A large number of targets were doing a mkdir -p openssl.  A parallel make
may execute several of these simultaniously, causing mkdir -p to race against
itself.  mkdir -p is not atomic (it does a stat and then a later mkdir) and
can fail under these conditions, causing a buildworld -j N to fail, so move
it to its own dependancy.