libnspr: bump to version 4.15
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit f234748a48d5640c8d1f4a84fcb1b5b9ac5bd77d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>