remove RTEXT_FILTER_MST as not yet widely supported

Author: jreppnow

libc-test/semver/linux.txt

@@ -1978,7 +1978,6 @@ RTEXT_FILTER_BRVLAN_COMPRESSED
 RTEXT_FILTER_CFM_CONFIG
 RTEXT_FILTER_CFM_STATUS
 RTEXT_FILTER_MRP
-RTEXT_FILTER_MST
 RTEXT_FILTER_SKIP_STATS
 RTEXT_FILTER_VF
 RTCF_DIRECTSRC

src/unix/linux_like/linux/mod.rs

@@ -2937,7 +2937,6 @@ pub const RTEXT_FILTER_SKIP_STATS: ::c_int = 1 << 3;
 pub const RTEXT_FILTER_MRP: ::c_int = 1 << 4;
 pub const RTEXT_FILTER_CFM_CONFIG: ::c_int = 1 << 5;
 pub const RTEXT_FILTER_CFM_STATUS: ::c_int = 1 << 6;
-pub const RTEXT_FILTER_MST: ::c_int = 1 << 7;
 
 // userspace compat definitions for RTNLGRP_*
 pub const RTMGRP_LINK: ::c_int = 0x00001;