[RFC] Support exec tracing on GNU/Linux and HP-UX

[Joel Brobecker]

> What do you think of the approach? I'll re-apply your patch on top
> of mine, and see what we get now.

The testsuite results on hpux seem to be a tad unstable (I get
some shakiness in follow-fork/vfork and maint.exp). but I see
the following differences too:

|       PASS |            | foll-exec.exp: insert first exec catchpoint        |
|       PASS |            | foll-exec.exp: continue to first exec catchpoint   |
|       FAIL | PASS       | foll-exec.exp: sync up after possible failure 2    |
|       FAIL | PASS       | foll-exec.exp: prepare to jump to execl call       |
|       FAIL | PASS       | foll-exec.exp: jump to execl call                  |
|       FAIL | PASS       | foll-exec.exp: prepare to jump to execv call       |
|       FAIL | PASS       | foll-exec.exp: jump to execv call                  |

On the left hand side, the results before the patch, and on the
right the result after your patch.

So, in terms of results, your patch looks good to me :).

-- 
Joel