Update nsprpub to allow ARM builds

[Bob-The-Marauder]

Replaced version 4.8 of nsprpub (circa 2009) with version 4.21 as downloaded from https://archive.mozilla.org/pub/nspr/releases/v4.21/src/nspr-4.21.tar.gz but simply unzipped, changed folder name to match current structure and rezipped.

[tburghart]

Errors reported during patching, don't know if they're relevant:

patching file nsprpub/configure
Hunk #1 succeeded at 6716 with fuzz 1 (offset 3198 lines).
Hunk #2 FAILED at 7738.
Hunk #3 FAILED at 8397.
Hunk #4 FAILED at 8405.
Hunk #5 FAILED at 8416.
Hunk #6 FAILED at 8433.
Hunk #7 FAILED at 8476.
Hunk #8 FAILED at 8500.
Hunk #9 FAILED at 8524.
Hunk #10 FAILED at 8552.
Hunk #11 FAILED at 8593.
Hunk #12 FAILED at 8632.
Hunk #13 FAILED at 8654.
Hunk #14 FAILED at 8676.
Hunk #15 FAILED at 8698.
Hunk #16 FAILED at 8830.
Hunk #17 FAILED at 8853.
Hunk #18 FAILED at 8873.
Hunk #19 succeeded at 8482 with fuzz 2 (offset 2693 lines).
17 out of 19 hunks FAILED -- saving rejects to file nsprpub/configure.rej
Skipping patch

[lemenkov]

@Bob-The-Marauder @tburghart just for your info - I'm maintaining a fork of this library @erlang-mozjs. Main differences are:

• Switch to NIF
• Upgrade to mozjs52

If you're interested then please try it and tell me about your experience. I'd love to get any feedback.