Oooops...
please delete this thread, because the kernel's info is from TWRP, sorry.
I flashed xiaomi.eu_multi_HM4X_V9.1.1.0.NAMCNEI_v9-7.1.zip and note the following in dmesg:
"Linux version 3.18.31-perf-gf92e02b (builder@c3-miui-ota-bd70.bj) (gcc version 4.9 20150123 (prerelease)"...