[C++] Use brace-equal initializers for default constructors.

Author: denizevrenci

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

@@ -1374,9 +1374,9 @@ private CharSequence generateFixedFlyweightCode(final String className, final in
 
         return String.format(
             "private:\n" +
-            "    char *m_buffer;\n" +
+            "    char *m_buffer = nullptr;\n" +
             "    std::uint64_t m_bufferLength;\n" +
-            "    std::uint64_t m_offset;\n" +
+            "    std::uint64_t m_offset = 0;\n" +
             "    std::uint64_t m_actingVersion;\n\n" +
             "    inline void reset(char *buffer, const std::uint64_t offset, const std::uint64_t bufferLength," +
             " const std::uint64_t actingVersion)\n" +
@@ -1391,7 +1391,7 @@ private CharSequence generateFixedFlyweightCode(final String className, final in
             "        m_actingVersion = actingVersion;\n" +
             "    }\n\n" +
             "public:\n" +
-            "    %1$s() : m_buffer(nullptr), m_offset(0) {}\n\n" +
+            "    %1$s() = default;\n\n" +
             "    %1$s(char *buffer, const std::uint64_t bufferLength, const std::uint64_t actingVersion)\n" +
             "    {\n" +
             "        reset(buffer, 0, bufferLength, actingVersion);\n" +
@@ -1441,7 +1441,7 @@ private CharSequence generateFixedFlyweightCode(final String className, final in
     private static CharSequence generateConstructorsAndOperators(final String className)
     {
         return String.format(
-            "    %1$s() : m_buffer(nullptr), m_bufferLength(0), m_offset(0) {}\n\n" +
+            "    %1$s() = default;\n\n" +
             "    %1$s(char *buffer, const std::uint64_t bufferLength)\n" +
             "    {\n" +
             "        reset(buffer, 0, bufferLength, sbeBlockLength(), sbeSchemaVersion());\n" +
@@ -1473,10 +1473,10 @@ private CharSequence generateMessageFlyweightCode(final String className, final
 
         return String.format(
             "private:\n" +
-            "    char *m_buffer;\n" +
-            "    std::uint64_t m_bufferLength;\n" +
+            "    char *m_buffer = nullptr;\n" +
+            "    std::uint64_t m_bufferLength = 0;\n" +
             "    std::uint64_t *m_positionPtr;\n" +
-            "    std::uint64_t m_offset;\n" +
+            "    std::uint64_t m_offset = 0;\n" +
             "    std::uint64_t m_position;\n" +
             "    std::uint64_t m_actingBlockLength;\n" +
             "    std::uint64_t m_actingVersion;\n\n" +