additional configuration options

[Vance Shipley]

In addition to the configuration options in listed in the top
level README, and available with ./configure --help, I find 
these additional options in erts/configure:

  --disable-megaco-flex-scanner-lineno  disable megaco flex scanner
  --enable-elib-malloc    use elib_malloc instead of normal malloc"
  --disable-fixalloc      disable the use of fix_alloc"

Can anyone shed some light on these?  

	-Vance