testing/infra/builder: dump defconfig to log

The defconfig is composed on-the-fly by test infra + tests.

Dump it to the logfile before running 'make olddefconfig' so it can
easily analysed when debugging.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/testing/infra/builder.py

@@ -17,6 +17,10 @@ class Builder(object):
         config_file = os.path.join(self.builddir, ".config")
         with open(config_file, "w+") as cf:
             cf.write(self.config)
+        # dump the defconfig to the logfile for easy debugging
+        self.logfile.write("> start defconfig\n" + self.config +
+                           "> end defconfig\n")
+        self.logfile.flush()
 
         cmd = ["make",
                "O={}".format(self.builddir),