nspr: Also update nspr.pc to 4.9.5

Earlier commits bumped the upstream version, but we need to update
our copy of the pkg-config file too.

(It'd probably be better to generate this at build time, otherwise
 this will be a trap people continually fall into)

Signed-off-by: Colin Walters <walters@verbum.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>