Remove racing from Mutex#locked? spec.
Remove racing from Mutex#locked? spec.

As with the Mutex#sleep spec, it's possible for the thread to
appear to be sleeping in the first lock call causing the spec to
proceed assuming the lock has completed. Modified to use a boolean
variable to indicate that the locking has actually completed.

lucaspinto/rubyspec,yous/rubyspec,iainbeeston/rubyspec,eregon/rubyspec,eregon/rubyspec,DawidJanczak/rubyspec,chesterbr/rubyspec,DavidEGrayson/rubyspec,iliabylich/rubyspec,ericmeyer/rubyspec,yaauie/rubyspec,nobu/rubyspec,mbj/rubyspec,saturnflyer/rubyspec,ruby/spec,alexch/rubyspec,mbj/rubyspec,Aesthetikx/rubyspec,benlovell/rubyspec,jannishuebl/rubyspec,atambo/rubyspec,iainbeeston/rubyspec,Aesthetikx/rubyspec,eregon/rubyspec,bl4ckdu5t/rubyspec,chesterbr/rubyspec,benlovell/rubyspec,sgarciac/spec,saturnflyer/rubyspec,ericmeyer/rubyspec,kachick/rubyspec,josedonizetti/rubyspec,ruby/rubyspec,kachick/rubyspec,sferik/rubyspec,agrimm/rubyspec,bl4ckdu5t/rubyspec,jannishuebl/rubyspec,scooter-dangle/rubyspec,scooter-dangle/rubyspec,DawidJanczak/rubyspec,kidaa/rubyspec,sferik/rubyspec,yaauie/rubyspec,teleological/rubyspec,bomatson/rubyspec,askl56/rubyspec,nobu/rubyspec,wied03/rubyspec,sgarciac/spec,kidaa/rubyspec,alexch/rubyspec,ruby/spec,ruby/spec,atambo/rubyspec,sgarciac/spec,askl56/rubyspec,josedonizetti/rubyspec,wied03/rubyspec,kachick/rubyspec,nobu/rubyspec,agrimm/rubyspec,ruby/rubyspec,BanzaiMan/rubyspec,DavidEGrayson/rubyspec,wied03/rubyspec,lucaspinto/rubyspec,bomatson/rubyspec,iliabylich/rubyspec,teleological/rubyspec,BanzaiMan/rubyspec,yous/rubyspec