hdf5_msb

[svn-r12312] Purpose:
H5_CFLAGS change

Description:
Made the threadsafe flags in config/freebsd H5_CFLAGS so that they are
not passed on to h5cc.

Solution:
If user applications need the threadsafe flag to link properly against
the threadsafe HDF5 library, we'll see linking errors in make-install
when threadsafe is enabled, and can revert this change.

Platforms tested:
mir only (very minor change)