Fix dbstop to find subfuncs of old-style class methods (bug #34804). * symtab.cc (find_submethod): New function to find subfunc in old-style class method. * symtab.h (find_method): Call find_submethod if function exists but not found through find_method. * symtab.h (find_submethod): Prototype for new function.

EXTRA_DIST += \
  m4/module.mk \
  m4/ax_blas.m4 \
  m4/ax_blas_f77_func.m4 \
  m4/ax_compare_version.m4 \
  m4/ax_lapack.m4 \
  m4/ax_openmp.m4 \
  m4/ax_pthread.m4 \
  m4/gnulib-cache.m4 \
  m4/libtool.m4 \
  m4/ltoptions.m4 \
  m4/ltsugar.m4 \
  m4/ltversion.m4 \
  m4/lt~obsolete.m4 \
  m4/pkg.m4