[NFC] Remove inaccurate comment

Summary:
r271558 moved getManagedStaticMutex's mutex from a function-local
static to using call_once, but left a comment added in r211424. That comment is
now erroneous, remove it.

Reviewers: zturner, chandlerc

Subscribers: aheejin, llvm-commits

Differential Revision: https://reviews.llvm.org/D46784

llvm-svn: 332175

llvm/lib/Support/ManagedStatic.cpp

@@ -28,9 +28,6 @@ static void initializeMutex() {
 }
 
 static sys::Mutex* getManagedStaticMutex() {
-  // We need to use a function local static here, since this can get called
-  // during a static constructor and we need to guarantee that it's initialized
-  // correctly.
   llvm::call_once(mutex_init_flag, initializeMutex);
   return ManagedStaticMutex;
 }