[Driver] Use StringRef::consume_front (NFC)

Author: kazutakahirata

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3704,11 +3704,11 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
   // --param ssp-buffer-size=
   for (const Arg *A : Args.filtered(options::OPT__param)) {
     StringRef Str(A->getValue());
-    if (Str.starts_with("ssp-buffer-size=")) {
+    if (Str.consume_front("ssp-buffer-size=")) {
       if (StackProtectorLevel) {
         CmdArgs.push_back("-stack-protector-buffer-size");
         // FIXME: Verify the argument is a valid integer.
-        CmdArgs.push_back(Args.MakeArgString(Str.drop_front(16)));
+        CmdArgs.push_back(Args.MakeArgString(Str));
       }
       A->claim();
     }