The included script carries /bin/sh shebang, though it doesn't work with dash. This is due to: trap "rm -f $TEMP_OUTPUT" ERR Where ERR is a ksh-specific extension. I'd suggest using EXIT instead. 'echo -n' & 'echo -ne' need to be replaced with printf too.
Also, the script is run as sh "${FILESDIR}/memcpy-to-memmove.sh" libflashplayer.so So simply changing the shebang doesn't help, this line (130 in the ebuild) must be fixed to run bash instead of sh.
*** This bug has been marked as a duplicate of bug 354073 ***