[C++]: make usable. aeron-io#643.

Author: tmontgomery

sbe-tool/src/main/cpp/otf/IrDecoder.h

@@ -53,9 +53,17 @@ class IrDecoder
  {
  }
 
- int decode(char *buffer, std::uint64_t length)
+ int decode(char *irBuffer, std::uint64_t length)
  {
  m_length = length;
+ if (m_length == 0)
+ {
+ return -1;
+ }
+ std::unique_ptr<char[]> buffer(new char[m_length]);
+ m_buffer = std::move(buffer);
+ std::memcpy(m_buffer.get(), irBuffer, m_length);
+
  return decodeIr();
  }
 
@@ -81,7 +89,7 @@ class IrDecoder
  return -1;
  }
 
- return decode(m_buffer.get(), m_length);
+ return decodeIr();
  }
 
  std::shared_ptr<std::vector<Token>> header()