This typically occurs as a result of an older version of GCC being used which has been built for Solaris 9.
Solaris 10 delivers a compatible version of GCC out of the box and it's this that should be used.
You can find the path to the compiler being used in Reality in /usr/realman/ver/files/build.conf
Look for the line which reads 'CcProg=…' Where ver is the current version, e.g. 14.0, 15.0
Modify this line to read 'CcProg=/usr/sfw/bin/gcc'
Rebuild Reality, which should now build fully.