core: increase the exit handler limit

Increase the maximum number of exit handlers since some tests now
require more that the previous limit.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81320
Signed-off-by: Thomas Wood <thomas.wood@intel.com>

lib/igt_core.c

@@ -977,7 +977,7 @@ void igt_waitchildren(void)
 
 /* exit handler code */
 #define MAX_SIGNALS		32
-#define MAX_EXIT_HANDLERS	5
+#define MAX_EXIT_HANDLERS	10
 
 static struct {
 	sighandler_t handler;