Add ubuntu-18 for linux-aarch

commit_hash:181a95a30c42dd39536b26f1b3b145903abb455c

Author: 4JustMe4

build/platform/linux_sdk/ya.make

@@ -31,6 +31,8 @@ ELSEIF (ARCH_X86_64)
 ELSEIF (ARCH_AARCH64)
     IF (OS_SDK == "ubuntu-16")
         DECLARE_EXTERNAL_RESOURCE(OS_SDK_ROOT sbr:309054781)
+    ELSEIF (OS_SDK == "ubuntu-18")
+        DECLARE_EXTERNAL_RESOURCE(OS_SDK_ROOT sbr:9897411969)
     ELSEIF (OS_SDK == "ubuntu-20")
         INCLUDE(${ARCADIA_ROOT}/build/platform/linux_sdk/ubuntu_20/aarch64.ya.make.inc)
         DECLARE_EXTERNAL_RESOURCE(OS_SDK_ROOT ${OS_SDK_SBR})