Removing LLVM_EXPLICIT, as MSVC 2012 was the last reason for requiring the macro. NFC; Clang edition.

llvm-svn: 229336

clang/lib/Analysis/CFG.cpp

@@ -156,7 +156,7 @@ public:
       return !(*this == rhs);
     }
 
-    LLVM_EXPLICIT operator bool() const {
+    explicit operator bool() const {
       return *this != const_iterator();
     }