no longer able to build default on MacOS X

[Ben Abbott]

My tip is 

$ hg tip
changeset:   21201:88b41a4711e2
bookmark:    @
tag:         tip
user:        Rik <address@hidden>
date:        Fri Feb 05 17:58:24 2016 -0800
summary:     maint: Correct names used in #ifdefs to prevent re-loading .h 
files.

The error message is …

  CXX      liboctave/numeric/liboctave_numeric_libnumeric_la-sparse-qr.lo
In file included from liboctave/numeric/sparse-qr.cc:30:
In file included from ./liboctave/util/oct-sparse.h:77:
/sw/include/suitesparse/cs.h:422:14: warning: 'cs_ci_house' has C-linkage 
specified, but returns user-defined type 'cs_complex_t' (aka 'complex<double>') 
which is incompatible with C
      [-Wreturn-type-c-linkage]
cs_complex_t cs_ci_house (cs_complex_t *x, double *beta, int n) ;
             ^
/sw/include/suitesparse/cs.h:562:14: warning: 'cs_cl_house' has C-linkage 
specified, but returns user-defined type 'cs_complex_t' (aka 'complex<double>') 
which is incompatible with C
      [-Wreturn-type-c-linkage]
cs_complex_t cs_cl_house (cs_complex_t *x, double *beta, cs_long_t n) ;
             ^
liboctave/numeric/sparse-qr.cc:2190:15: error: use 'template' keyword to treat 
'tall_solve' as a dependent template name
  return rep->tall_solve<RHS_T, RET_T> (b, info);
              ^
              template 
liboctave/numeric/sparse-qr.cc:2198:15: error: use 'template' keyword to treat 
'wide_solve' as a dependent template name
  return rep->wide_solve<RHS_T, RET_T> (b, info);
              ^
              template 
2 warnings and 2 errors generated.

I’ve deleted the files below from my build tree.

         libinterp/oct-conf.h
         libinterp/oct-conf-features.h

I suspect the problem was introduced by changeset 21186:7f35125714b4

        http://hg.savannah.gnu.org/hgweb/octave/rev/7f35125714b4

Ben