hdf5_ep

[svn-r19592] Bug fix: since the addition of 
    RUNSERIAL=${RUNSERIAL="env LDR_CNTRL=MAXDATA=0x20000000@DSA"}
kind of mess things up for the parallel HDF5 configure.
Changed it to 
    RUNSERIAL=${RUNSERIAL="env LDR_CNTRL=MAXDATA=0x20000000@DSA MP_PROCS=1 MP_TASKS_PER_NODE=1 poe"}
if --enable-parallel.

Also merge powerpc-ibm-aix5.x with ibm-aix by making powerpc-ibm-aix5.x to
source ibm-aix just like ibm-aix6.x.  This is in preparation that all AIX
platforms will eventually just use ibm-aix directly.

Fixed a small problme in ibm-flags: some older xlc (e.g. v7.1) prints the
version information with a leading blank. So, accommodate this pattern by
removing the "^".

Tested: LLNL uP, 32/64bits, serial/parallel. (parallel has tests failed
but this change is mainily for configure issues.)
Also tested BP, 32/64bits but serial only.