[cpp] Minor fix to cpp generator output formatting.

Author: mjpt777

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java

@@ -309,7 +309,7 @@ private static void generateGroupClassHeader(
             indent + "#else\n" +
             indent + "    template<class Func> inline void forEach(Func&& func)\n" +
             indent + "    {\n" +
-            indent + "        while(hasNext())\n" +
+            indent + "        while (hasNext())\n" +
             indent + "        {\n" +
             indent + "            next(); func(*this);\n" +
             indent + "        }\n" +