Can't compile with --with-rtldebug

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=4063

Reported by Martin Stjernholm mast@roxen.com

Compiling pike with --with-rtldebug causes errors in pike_types.c:

/home/mast/Pike/stable/src/pike_types.c:2092: error: invalid storage class
for function ‘low_match_types2’
/home/mast/Pike/stable/src/pike_types.c:2143: warning: implicit declaration
of function ‘low_match_types2’
/home/mast/Pike/stable/src/pike_types.c:2143: warning: assignment makes
pointer from integer without a cast
/home/mast/Pike/stable/src/pike_types.c: At top level:
/home/mast/Pike/stable/src/pike_types.c:2166: error: conflicting types for
‘low_match_types2’
/home/mast/Pike/stable/src/pike_types.c:2143: error: previous implicit
declaration of ‘low_match_types2’ was here

etc etc.

Commenting out the PIKE_TYPE_DEBUG define near the top avoids the problem.

The same thing occurs in both 7.4 and 7.6.