MFH: r546113
devel/nspr: update to 4.28
Changes: http://mozilla.6506.n7.nabble.com/ANNOUNCE-NSPR-4-28-Release-td386342.html
ABI: https://abi-laboratory.pro/tracker/timeline/nspr/
Reported by: Repology
Approved by: ports-secteam blanket (required by Firefox 81)