[PATCH] Update auxv cache when inferior pid is 0 (no inferior)

[Luis Machado <luis.machado@arm.com>]

While adding support for MTE corefiles and running the MTE corefile tests,
I noticed a strange situation where loading the symbol file + core file
through the command line has a different behavior compared to firing up
GDB, loading the symbol file with the "file" command and then loading the
core file with the "core" command.

I tracked this down to gdb/auxv.c:get_auxv_inferior_data returning empty
auxv data for pid 0, which gets cached. This is triggered by attempting to
read auxv data for the exec target.

In the early stages of reading the core file, we're still using inferior pid
0, so when we attempt to read auxv to determine corefile features, we get the
cached empty data vector again. This breaks core_gdbarch setup.

The fix, suggested by John Baldwin, prevents caching auxv data for pid 0.
---
 gdb/auxv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/auxv.c b/gdb/auxv.c
index 6154988f6dd..33a829a7573 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -361,7 +361,7 @@ get_auxv_inferior_data (struct target_ops *ops)
   struct inferior *inf = current_inferior ();
 
   info = auxv_inferior_data.get (inf);
-  if (info == NULL)
+  if (info == NULL || inf->pid == 0)
     {
       info = auxv_inferior_data.emplace (inf);
       info->data = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL);
-- 
2.25.1