[gimp] devel-docs: we must still restart a plug-in to debug with SIGCONT.

[Jehan <jehanp src gnome org>]

commit fadda1b8dbb8ea8f6ae77868a889512d518f982a
Author: Jehan <jehan girinstud io>
Date:   Sun Aug 22 19:01:10 2021 +0200

    devel-docs: we must still restart a plug-in to debug with SIGCONT.
    
    Commit 59f2ba44c7 changed the devel docs to tell that on Linux, just
    running the gdb command `continue` is enough to restart the plug-in
    process. Maybe it is true on some specific setups, so I leave this part
    of the note, but for sure it never worked for me. I may run `continue`
    as many times as I want, the process stays stopped until I explicitly
    send a SIGCONT signal (our code raises itself a SIGSTOP which requires a
    SIGCONT for continuation of the process).
    
    Maybe in some configurations, gdb actually sends a SIGCONT when
    `continue` is run but not in others? No idea.
    
    Anyway I add back the part about sending a SIGCONT too, then people can
    test and choose which procedure works for them.

 devel-docs/debug-plug-ins.txt | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/devel-docs/debug-plug-ins.txt b/devel-docs/debug-plug-ins.txt
index 9dbe570368..e6584016f3 100644
--- a/devel-docs/debug-plug-ins.txt
+++ b/devel-docs/debug-plug-ins.txt
@@ -69,11 +69,14 @@ To use a debugger on a C-language plug-in:
      (e.g. "gdb> attach <pid>")
      Expect the debugger to say where the plug-in is suspended.
 
-
   5. In the debugger, set breakpoints (or examine memory, or step, etc.)
 
   6. Windows: resume the plug-in process with "gimp-debug-resume.exe <pid>"
-     (On Linux, the gdb continue command resumes the attached process.)
+
+     Linux and Unix-like: the gdb `continue` command might resume the
+     attached process. Possibly you will have to send a SIGCONT signal:
+
+         kill -SIGCONT <pid>
 
   7. In the debugger, enter "continue". Expect the plug-in to resume under
      control of the debugger and pause at breakpoints.