ntp: Vendor import of ntp-4.2.8p18 MFC: 3 days Merge commit '1f833b3fc9968c3dd7ed79ccf0525ebf16c891ad' into main
MFV r338092: ntp 4.2.8p12. Relnotes: yes
MFV r330102: ntp 4.2.8p11
MFV r315791: ntp 4.2.8p10.
MFV r308954: ntp 4.2.8p9. Approved by: so
MFV ntp 4.2.8p1 (r258945, r275970, r276091, r276092, r276093, r278284) Thanks to roberto for providing pointers to wedge this into HEAD. Approved by: roberto