[clang][driver][NFC] Add hasShadowCallStack to SanitizerArgs

[paulkirth]

Summary

Currently, we can't check if ShadowCallStack is present in Args the same
way we handle other sanitizers. This is preparatory work for planned
driver changes to how we handle ShadowCallStack.

clang/include/clang/Driver/SanitizerArgs.h

public:
   bool hasMemtagGlobals() const {
     return Sanitizers.has(SanitizerKind::MemtagGlobals);
   }
   const std::string &getMemtagMode() const {
     assert(!MemtagMode.empty());
     return MemtagMode;
   }
 
+  bool hasShadowCallStack() const {
+    return Sanitizers.has(SanitizerKind::ShadowCallStack);
+  }
+
   bool requiresPIE() const;
   bool needsUnwindTables() const;
   bool needsLTO() const;
   bool linkRuntimes() const { return LinkRuntimes; }
   bool linkCXXRuntimes() const { return LinkCXXRuntimes; }
   bool hasCrossDsoCfi() const { return CfiCrossDso; }
   bool hasAnySanitizer() const { return !Sanitizers.empty(); }
   void addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args,
                llvm::opt::ArgStringList &CmdArgs, types::ID InputType) const;
 };
 
 }  // namespace driver
 }  // namespace clang
 
 #endif