message: Add SLIC_INFO_IF and SLIC_DEBUG_IF
diff: , __LINE__ ); \
  } while ( axom::slic::detail::false_value )
  +/*!
  + * \def SLIC_INFO_IF( EXP, msg )
  + * \brief Logs an Info message iff EXP is true
  + * \param [in] EXP user-supplied boolean expression.
  + * \param [in] msg user-supplied message.
  + * \note The SLIC_INFO_IF macro is always active.
  + *
  + * Usage:
  + * \code
  + * SLIC_INFO_IF( (val < 0), "my_val should always be positive" );
  + * \endcode
  + *
  + */
  +#define SLIC_INFO_IF( EXP, msg ) \
  + do { \
  + if ( EXP ) { \
  + std::ostringstream oss; \
  + oss << msg; \
  + axom::slic::logMessage(axom::slic::message::Info \
  + , oss.str() \
  + ,__FILE__ \
  + , __LINE__ ); \
  + } \
  + } while ( axom::slic::detail::false_value )
  +
  #ifdef AXOM_DEBUG
  /*!
  , __LINE__ ); \
  } while ( axom::slic::detail::false_value )
  +/*!
  + * \def SLIC_DEBUG_IF( EXP, msg )
  + * \brief Logs an Debug message iff EXP is true
  + * \param [in] EXP user-supplied boolean expression.
  + * \param [in] msg user-supplied message.
  + * \note The SLIC_DEBUG_IF macro is always active.
  + *
  + * Usage:
  + * \code
  + * SLIC_DEBUG_IF( (val < 0), "my_val should always be positive" );
  + * \endcode
  + *
  + */
  +#define SLIC_DEBUG_IF( EXP, msg ) \
  + do { \
  + if ( EXP ) { \
  + std::ostringstream oss; \
  + oss << msg; \
  + axom::slic::logMessage(axom::slic::message::Debug \
  + , oss.str() \
  + ,__FILE__ \
  + , __LINE__ ); \
  + } \
  + } while ( axom::slic::detail::false_value )
  +
  #else // turn off debug macros
  #define SLIC_DEBUG( ignore_EXP ) ( (void)0 )
  