[PATCH 5/9] gdb: remove final user of the executable_changed observer

[Andrew Burgess <aburgess@redhat.com>]

This commit continues with the task started in the previous commit,
and is similar in many ways.

The goal of the next couple of commits is to expose the
executable_changed observable in the Python API as an event.  Before I
do this I would like to remove the additional call to the
executable_changed observable which can be found in the reread_symbols
function in the symfile.c file, as I don't believe that this use
actually corresponds to a change in the current executable.

The previous commit removed one user of the executable_changed
observable and replaced it with a new_obfile observer instead, and
this commit does the same thing.

In auxv.c we use the executable_changed observable to call
invalidate_auxv_cache, which then calls:

  invalidate_auxv_cache_inf (current_inferior ());

The auxv cache is already (additionally) cleared when an inferior
exits and when an inferior appears.

As with the previous commit, I think we can safely replace the use of
the executable_changed observable with a use of the new_obfile
observable.  All the tests still pass, and with some locally placed
printf calls, I think that the cache is still being cleared in all the
cases that should matter.
---
 gdb/auxv.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/gdb/auxv.c b/gdb/auxv.c
index 3c27c1f1ffe..9f599b04a4f 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -344,12 +344,14 @@ invalidate_auxv_cache_inf (struct inferior *inf)
   auxv_inferior_data.clear (inf);
 }
 
-/* Invalidate current inferior's auxv cache.  */
+/* Invalidate current inferior's auxv cache when all symbol table data is
+   cleared (indicated by OBJFILE being nullptr).  */
 
 static void
-invalidate_auxv_cache (void)
+auxv_new_objfile_observer (struct objfile *objfile)
 {
-  invalidate_auxv_cache_inf (current_inferior ());
+  if (objfile == nullptr)
+    invalidate_auxv_cache_inf (current_inferior ());
 }
 
 /* See auxv.h.  */
@@ -613,5 +615,5 @@ This is information provided by the operating system at program startup."));
   /* Observers used to invalidate the auxv cache when needed.  */
   gdb::observers::inferior_exit.attach (invalidate_auxv_cache_inf, "auxv");
   gdb::observers::inferior_appeared.attach (invalidate_auxv_cache_inf, "auxv");
-  gdb::observers::executable_changed.attach (invalidate_auxv_cache, "auxv");
+  gdb::observers::new_objfile.attach (auxv_new_objfile_observer, "auxv");
 }
-- 
2.25.4