Pedro reported a crash of code compiled with stabs on

gdb_assert(gsymbol->language_specific.cplus_specific != NULL);

in symbol_get_demangled_name. The problem was that 
stabsread.c:define_symbol was calling cp_scan_for_anonymous_namespaces 
before setting the name. I corrected that but there other case, and for 
those I changed the assertion into an if statement that returns null 
since symbol_natural_name depends on symbol_get_demangled_name to return 
null in order to fall back to gsymbol->name.

This was tested by running the test suite and compiling
member-ptr with -gstabs breaking on main executing a few commands and 
printing some values.

Sami