rewrite_to_chrome_style: Use constexpr as backdoor to get consistency

tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp

Index: tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
diff --git a/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp b/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
index 2d6713c89c9e4f31f96272c6b64e9e5f95b494f9..5df98a529aea727ad79d3e991669a5db34c12b36 100644
--- a/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
+++ b/tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp
@@ -475,6 +475,9 @@ bool IsProbablyConst(const clang::VarDecl& decl,
   if (type.isVolatileQualified())
     return false;
 
+  if (decl.isConstexpr())
+    return true;
+
   // Parameters should not be renamed to |kFooBar| style (even if they are
   // const and have an initializer (aka default value)).
   if (clang::isa<clang::ParmVarDecl>(&decl))