configure updates

[Satish Balay]

I've pushed a new option to configure [appears to be required by a few
external packages]

--download-netlib-blas-lapack=1

Also - I'd like to push the following change

chnage:
  --with-f90-header=f90_rs6000.h --with-f90-source=f90_rs6000.c 
to:
  --with-f90-interface=rs6000

With the following help string:
--with-f90-interface=<type> : Specify  compiler type for eg: intel8,solaris,rs6000,IRIX,win32,absoft,t3e,dec,cray_x1,hpux

Satish