Fix typos in comments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34456 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Target.td

@@ -39,7 +39,7 @@ class Register<string n> {
   int SpillAlignment = 0;
 
   // Aliases - A list of registers that this register overlaps with.  A read or
-  // modification of this register can potentially read or modifie the aliased
+  // modification of this register can potentially read or modify the aliased
   // registers.
   //
   list<Register> Aliases = [];