Avoid redundant text -in -Dr output

Avoid redundant text -in -Dr output

There is an optimization in regcomp.c which saves memory when used, but
which caused -Dr output to display the same code points twice.
I didn't add a test to ext/re/t/regop.t because this only happens for a
Unicode property, under certain circumstances, and that triggers a lot
of other regex patterns to be compiled which are subject to change, so
the test would frequently have to be updated.  This only affects
debugging output anyway.