Bug 915312 - Pre: Remove unneeded checks from fennec-copy-code.
Bug 915312 - Pre: Remove pbkdf2SHA1.

Squashed commits:
  * Bug 915312 - TO BE FOLDED: Allocate less.
  * Bug 915312 - TO BE FOLDED: Allocate even less.
Bug 915312 - Part 1: Add NativeCrypto exposing pbkdf2SHA256.
Bug 915312 - Part 2: Import sha1 test and invalid len arg test from m-c.
Bug 915312 - Part 3: Add libmozglue.so from tbpl.

push: https://tbpl.mozilla.org/?tree=Fx-Team&rev=4f2c6a223cb4
Bug 915312 - Add SHA-256 and SHA-1 NativeCrypto methods. r=nalexander