utils/genrandconfig: reduce the maximum "size" of random configurations

genrandconfig is used by the Buildroot autobuilders to generate
semi-random configurations that we build test. As part of this, we use
"make randpackageconfig" to randomize the selection of packages,
together with a KCONFIG_PROBABILITY value, which indicates the
probabibility for each option to be enabled. This probability is
itself randomized, between 1% and 30% for every build.

However, with our increasing number of packages (over 2900), when we
use a 30% probability for options to be enabled, it means a *lot* of
options are enabled, causing very large configurations to be
tested. These configurations are not very realistic, and they take
ages to build on our autobuilders: we have builds that take 4, 5 or
even 7 hours to build.

In order to test a larger number of configurations and therefore a
larger variety of configurations, this commit reduces the maximum
probability to 20%.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 0e64537917)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/genrandconfig

@@ -412,7 +412,7 @@ def gen_config(args):
             return 1
         bounded_loop -= 1
         subprocess.check_call(["make", "O=%s" % args.outputdir, "-C", args.buildrootdir,
-                               "KCONFIG_PROBABILITY=%d" % randint(1, 30),
+                               "KCONFIG_PROBABILITY=%d" % randint(1, 20),
                                "randpackageconfig"])
 
         if fixup_config(sysinfo, configfile):