vchoi_fork

[svn-r18929] New feature:
Added ibm-flags to display the IBM XL compilers version information so that configure
can report them in the configure summary and the libhdf5.settings file.
For now, only the C compiler (xlc) versions are displayed.

Also moved the C compiler options setting from ibm-aix to ibm-flags.

Tested: NCSA Blue-print, both 32 and 64 bit modes.