Fix known typos

Sweep the codebase for common typos. Includes some changes to visible function
names that were misspelt.

llvm-svn: 200018
diff --git a/llvm/lib/CodeGen/ScheduleDAG.cpp b/llvm/lib/CodeGen/ScheduleDAG.cpp
index 75e3790..bd4c0e2 100644
--- a/llvm/lib/CodeGen/ScheduleDAG.cpp
+++ b/llvm/lib/CodeGen/ScheduleDAG.cpp
@@ -63,7 +63,7 @@
 /// not already.  It also adds the current node as a successor of the
 /// specified node.
 bool SUnit::addPred(const SDep &D, bool Required) {
-  // If this node already has this depenence, don't add a redundant one.
+  // If this node already has this dependence, don't add a redundant one.
   for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
          I != E; ++I) {
     // Zero-latency weak edges may be added purely for heuristic ordering. Don't