analyzer: handle <error.h> at -O0 [PR115724]

At -O0, glibc's:

__extern_always_inline void
error (int __status, int __errnum, const char *__format, ...)
{
  if (__builtin_constant_p (__status) && __status != 0)
    __error_noreturn (__status, __errnum, __format, __builtin_va_arg_pack ());
  else
    __error_alias (__status, __errnum, __format, __builtin_va_arg_pack ());
}

becomes just:

__extern_always_inline void
error (int __status, int __errnum, const char *__format, ...)
{
  if (0)
    __error_noreturn (__status, __errnum, __format, __builtin_va_arg_pack ());
  else
    __error_alias (__status, __errnum, __format, __builtin_va_arg_pack ());
}

and thus calls to "error" are calls to "__error_alias" by the
time -fanalyzer "sees" them.

Handle them with more special-casing in kf.cc.

gcc/analyzer/ChangeLog:
	PR analyzer/115724
	* kf.cc (register_known_functions): Add __error_alias and
	__error_at_line_alias.

gcc/testsuite/ChangeLog:
	PR analyzer/115724
	* c-c++-common/analyzer/error-pr115724.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>