travis: set CI for distcheck

on distcheck TM test is called but it can fail under Travis.

Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>
Reviewed-by: Dmitry Eremin-Solenikov <dmitry.ereminsolenikov@linaro.org>

scripts/ci/distcheck.sh

@@ -14,4 +14,8 @@ make distcheck
 
 make clean
 
+# Ignore possible failures there because these tests depends on measurements
+# and systems might differ in performance.
+export CI="true"
+
 make distcheck DISTCHECK__CONFIGURE_FLAGS=--disable-abi-compat