Add explicit keywords and remove spurious trailing semicolons.

llvm-svn: 41482
diff --git a/llvm/lib/CodeGen/PhysRegTracker.h b/llvm/lib/CodeGen/PhysRegTracker.h
index f5a2402..2717e33 100644
--- a/llvm/lib/CodeGen/PhysRegTracker.h
+++ b/llvm/lib/CodeGen/PhysRegTracker.h
@@ -26,7 +26,7 @@
         std::vector<unsigned> regUse_;
 
     public:
-        PhysRegTracker(const MRegisterInfo& mri)
+        explicit PhysRegTracker(const MRegisterInfo& mri)
             : mri_(&mri),
               regUse_(mri_->getNumRegs(), 0) {
         }