* value.h (value_contents_equal): New prototype.

* value.h (value_contents_equal): New prototype.
* value.c (value_contents_equal): New function.
* varobj.c: Include "exceptions.h" and "gdb_assert.h".  Don't
include <math.h>.
(varobj_set_value): Initialize error to zero.
(varobj_update): Rename error2 to error and initialize it to zero.
Slightly change the wording of some comments.
(my_value_equal): Reimplement using TRY_CATCH and
value_contents_equal.