Update terminology from "multithread" to "multi-threaded"

Author: idoleat

concurrency-primer.tex

@@ -939,7 +939,7 @@ \subsection{ABA problem}
 At the end, the dangling pointer could either point to garbage or trigger segmentation fault.
 It could be even worse if nested ABA problem occurs in thread B.
 Also, the possibility to allocate a job with same address could be higher when using memory pool, meaning that more chances to have ABA problem occurred.
-In fact, pre-allocated memory should be used to achieve lock-free since \monobox{malloc} could have mutex involved in multithreaded environment.
+In fact, pre-allocated memory should be used to achieve lock-free since \monobox{malloc} could have mutex involved in multi-threaded environment.
 
 Failure to recognize changed target object through comparison can result in stale information.
 The general concept of solving this problem involves adding more information to make different state distinguishable, and then making a decision on whether to act on the old state or retry with the new state.