[RFC PATCH 1/3] gdb/nat: Use procfs(5) indexes in linux_common_core_of_thread

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

The code and comment reference stat fields by made-up indexes.  The
procfs(5) man page, which describes the /proc/PID/stat file, has a numbered
list of these fields so it's more convenient to use those numbers instead.

This is currently an implementation detail inside the function so it's
not really relevant with the code as-is, but a future patch will do some
refactoring which will make the index more prominent.

Therefore, make this change in a separate patch so that it's simpler to
review.
---
 gdb/nat/linux-osdata.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/gdb/nat/linux-osdata.c b/gdb/nat/linux-osdata.c
index c9192940f236..172fea5cea85 100644
--- a/gdb/nat/linux-osdata.c
+++ b/gdb/nat/linux-osdata.c
@@ -75,10 +75,10 @@ linux_common_core_of_thread (ptid_t ptid)
   if (pos == std::string::npos)
     return -1;
 
-  /* If the first field after program name has index 0, then core number is
-     the field with index 36 (so, the 37th).  There's no constant for that
-     anywhere.  */
-  for (int i = 0; i < 37; ++i)
+  /* If the first field after program name has index 3, then core number is
+     the field with index 39.  These are the indexes shown in the procfs(5)
+     man page.  */
+  for (int i = 3; i <= 39; ++i)
     {
       /* Find separator.  */
       pos = content->find_first_of (' ', pos);