[Java] Fix generated codec for string_view with C++17.

Author: mjpt777

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

@@ -1306,7 +1306,7 @@ private CharSequence generateArrayProperty(
                 indent + "             throw std::runtime_error(\"string too large for put%2$s [E106]\");\n" +
                 indent + "        }\n\n" +
                 indent + "        size_t length = srcLength < %4$d ? srcLength : %4$d;\n" +
-                indent + "        std::memcpy(m_buffer + m_offset + %3$d, str.c_str(), length);\n" +
+                indent + "        std::memcpy(m_buffer + m_offset + %3$d, str.data(), length);\n" +
                 indent + "        for (size_t start = srcLength; start < length; ++start)\n" +
                 indent + "        {\n" +
                 indent + "            m_buffer[m_offset + %3$d + start] = 0;\n" +