Remove exception_none

Now that gdb_exception has a constructor, there's no need for
exception_none.  This patch removes it.

gdb/ChangeLog
2019-04-25  Tom Tromey  <tromey@adacore.com>

	* xml-support.c (gdb_xml_parser::gdb_xml_parser): Update.
	* python/py-value.c (valpy_getitem, valpy_nonzero): Update.
	* python/py-inferior.c (infpy_write_memory, infpy_search_memory):
	Update.
	* python/py-breakpoint.c (bppy_set_condition, bppy_set_commands):
	Update.
	* mi/mi-interp.c (mi_interp::exec): Update.
	* linespec.c (parse_linespec): Update.
	* infcall.c (run_inferior_call): Update.
	* guile/scm-value.c (gdbscm_value_to_lazy_string): Update.
	* guile/scm-symbol.c (gdbscm_lookup_symbol)
	(gdbscm_lookup_global_symbol): Update.
	* guile/scm-param.c (gdbscm_parameter_value): Update.
	* guile/scm-frame.c (gdbscm_frame_read_register)
	(gdbscm_frame_read_var): Update.
	* guile/scm-breakpoint.c (gdbscm_register_breakpoint_x): Update.
	* exec.c (try_open_exec_file): Update.
	* event-top.c (gdb_rl_callback_read_char_wrapper_noexcept)
	(gdb_rl_callback_handler): Update.
	* common/common-exceptions.h (exception_none): Don't declare.
	* common/common-exceptions.c (exception_none): Don't define.
	(struct catcher) <exception>: Update.
	* cli/cli-interp.c (safe_execute_command): Update.
	* breakpoint.c (insert_bp_location, location_to_sals): Update.

gdb/python/py-breakpoint.c

@@ -445,7 +445,7 @@ bppy_set_condition (PyObject *self, PyObject *newvalue, void *closure)
   gdb::unique_xmalloc_ptr<char> exp_holder;
   const char *exp = NULL;
   gdbpy_breakpoint_object *self_bp = (gdbpy_breakpoint_object *) self;
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
 
   BPPY_SET_REQUIRE_VALID (self_bp);
 
@@ -515,7 +515,7 @@ static int
 bppy_set_commands (PyObject *self, PyObject *newvalue, void *closure)
 {
   gdbpy_breakpoint_object *self_bp = (gdbpy_breakpoint_object *) self;
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
 
   BPPY_SET_REQUIRE_VALID (self_bp);
 

gdb/python/py-inferior.c

@@ -546,7 +546,7 @@ infpy_read_memory (PyObject *self, PyObject *args, PyObject *kw)
 static PyObject *
 infpy_write_memory (PyObject *self, PyObject *args, PyObject *kw)
 {
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
   Py_ssize_t buf_len;
   const gdb_byte *buffer;
   CORE_ADDR addr, length;
@@ -682,7 +682,7 @@ get_char_buffer (PyObject *self, Py_ssize_t segment, char **ptrptr)
 static PyObject *
 infpy_search_memory (PyObject *self, PyObject *args, PyObject *kw)
 {
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
   CORE_ADDR start_addr, length;
   static const char *keywords[] = { "address", "length", "pattern", NULL };
   PyObject *start_addr_obj, *length_obj;

gdb/python/py-value.c

@@ -903,7 +903,7 @@ get_field_type (PyObject *field)
 static PyObject *
 valpy_getitem (PyObject *self, PyObject *key)
 {
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
   value_object *self_value = (value_object *) self;
   gdb::unique_xmalloc_ptr<char> field;
   struct type *base_class_type = NULL, *field_type = NULL;
@@ -1480,7 +1480,7 @@ valpy_absolute (PyObject *self)
 static int
 valpy_nonzero (PyObject *self)
 {
-  struct gdb_exception except = exception_none;
+  struct gdb_exception except;
   value_object *self_value = (value_object *) self;
   struct type *type;
   int nonzero = 0; /* Appease GCC warning.  */