Travis-ci: specify KCONFIG_ALLCONFIG for randconfig

The file provided contains symbols that must be set to certain values.
This then prevents random build breakage in travis due to
known-incompatible symbol selections.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>

scripts/travis-build

@@ -4,7 +4,7 @@ $CC --version
 
 # random config or default config
 if [[ "${RANDCONFIG}" == "y" ]]; then
-    make -C xen randconfig
+    make -C xen KCONFIG_ALLCONFIG=tools/kconfig/allrandom.config randconfig
 else
     make -C xen defconfig
 fi