We may abort the process of detaching threads with multiple SIGINTs - which are
being sent during a testcase terminating its child GDB.

Some of the threads may not be properly PTRACE_DETACHed which hurts if they
should have been detached with SIGSTOP (as they are accidentally left running
on the debugger termination).

diff -dup -rup gdb-7.10.50.20160106-orig/gdb/defs.h gdb-7.10.50.20160106/gdb/defs.h
--- gdb-7.10.50.20160106-orig/gdb/defs.h	2016-01-09 15:06:57.658172875 +0100
+++ gdb-7.10.50.20160106/gdb/defs.h	2016-01-09 15:07:12.431264378 +0100
@@ -145,6 +145,9 @@ extern void set_quit_flag (void);
 /* Flag that function quit should call quit_force.  */
 extern volatile int sync_quit_force_run;
 
+#ifdef NEED_DETACH_SIGSTOP
+extern int quit_flag_cleanup;
+#endif
 extern int immediate_quit;
 
 extern void quit (void);
diff -dup -rup gdb-7.10.50.20160106-orig/gdb/extension.c gdb-7.10.50.20160106/gdb/extension.c
--- gdb-7.10.50.20160106-orig/gdb/extension.c	2016-01-06 02:48:37.000000000 +0100
+++ gdb-7.10.50.20160106/gdb/extension.c	2016-01-09 15:07:12.434264396 +0100
@@ -833,6 +833,11 @@ check_quit_flag (void)
   int i, result = 0;
   const struct extension_language_defn *extlang;
 
+#ifdef NEED_DETACH_SIGSTOP
+  if (quit_flag_cleanup)
+    return 0;
+
+#endif
   ALL_ENABLED_EXTENSION_LANGUAGES (i, extlang)
     {
       if (extlang->ops->check_quit_flag != NULL)
diff -dup -rup gdb-7.10.50.20160106-orig/gdb/top.c gdb-7.10.50.20160106/gdb/top.c
--- gdb-7.10.50.20160106-orig/gdb/top.c	2016-01-06 02:48:38.000000000 +0100
+++ gdb-7.10.50.20160106/gdb/top.c	2016-01-09 15:07:12.432264384 +0100
@@ -1557,7 +1557,13 @@ quit_force (char *args, int from_tty)
   qt.args = args;
   qt.from_tty = from_tty;
 
+#ifndef NEED_DETACH_SIGSTOP
   /* We want to handle any quit errors and exit regardless.  */
+#else
+  /* We want to handle any quit errors and exit regardless but we should never
+     get user-interrupted to properly detach the inferior.  */
+  quit_flag_cleanup = 1;
+#endif
 
   /* Get out of tfind mode, and kill or detach all inferiors.  */
   TRY
diff -dup -rup gdb-7.10.50.20160106-orig/gdb/utils.c gdb-7.10.50.20160106/gdb/utils.c
--- gdb-7.10.50.20160106-orig/gdb/utils.c	2016-01-09 15:06:57.654172850 +0100
+++ gdb-7.10.50.20160106/gdb/utils.c	2016-01-09 15:07:12.433264390 +0100
@@ -122,6 +122,13 @@ int job_control;
 
 int immediate_quit;
 
+#ifdef NEED_DETACH_SIGSTOP
+/* Nonzero means we are already processing the quitting cleanups and we should
+   no longer get aborted.  */
+
+int quit_flag_cleanup;
+
+#endif
 /* Nonzero means that strings with character values >0x7F should be printed
    as octal escapes.  Zero means just print the value (e.g. it's an
    international character, and the terminal or window can cope.)  */