Cleanup new configure generated files in distclean
Cleanup new configure generated files in distclean

Some newly added files also need to be cleaned up.

Likewise, ./libdecnumber/Makefile has been renamed to
libdecnumber/Makefile.libdecnumber

Signed-off-by: Paul E. Murphy <bcb79dc2d3103f301c432ff2685f8b89fad82826@linux.vnet.ibm.com>

gftg85/libdfp,gftg85/libdfp,gftg85/libdfp,gftg85/libdfp