Fix warnings when -Wextra-semi is enabled

Also, add argument -Wextra-semi if supported by the compiler.

CMakeLists.txt

@@ -86,6 +86,10 @@ check_cxx_compiler_flag("-Wsuggest-override" HAVE_SUGGEST_OVERRIDE)
 if (HAVE_SUGGEST_OVERRIDE)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wsuggest-override")
 endif()
+check_cxx_compiler_flag("-Wextra-semi" HAVE_EXTRA_SEMI)
+if (HAVE_EXTRA_SEMI)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wextra-semi")
+endif()
 
 if (WSREP_LIB_STRICT_BUILD_FLAGS)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Weffc++")

dbsim/db_server.hpp

@@ -77,6 +77,6 @@ namespace db
         std::vector<std::shared_ptr<db::client>> clients_;
         std::vector<boost::thread> client_threads_;
     };
-};
+}
 
 #endif // WSREP_DB_SERVER_HPP

dbsim/db_tls.hpp

@@ -57,6 +57,6 @@ namespace db
         static void init(int mode);
         static std::string stats();
     };
-};
+}
 
 #endif // WSREP_DB_TLS_HPP

include/wsrep/provider_options.hpp

@@ -57,7 +57,7 @@ namespace wsrep
         class option_value
         {
         public:
-            virtual ~option_value(){}
+            virtual ~option_value() {}
             virtual const char* as_string() const = 0;
             virtual const void* get_ptr() const = 0;
         };

include/wsrep/thread.hpp

@@ -52,4 +52,4 @@ namespace wsrep
     }
 
     std::ostream& operator<<(std::ostream&, const thread::id&);
-};
+}