NativeCrypto: DSA keys do not always have parameters

DSA keys do not always have parameters. When validating a certificate
chain, the DSA key will inherit parameters from the next DSA key up the
chain if DSAPublicKey#getParams() returns "null".

Change-Id: I052b42219829157ebdf148abb53048044cc83f8d
Fix BigDecimal precision when constructed from String.

Bug: https://code.google.com/p/android/issues/detail?id=43480
Change-Id: Id42e4458323d7ab3dafb2dec84909096988e4365
Add support for Libcore.os.exec*()

Add Libcore support for execv() and execve().
This allows java programs to execute other programs
without having to write jni wrappers.

Change-Id: I82ddc069b5812ebd40f06b7f65ce173d496e0597
Remove fixed CipherTest "known failure"

Bug: 3387688
Change-Id: I620ae46fcf3681120c958dc847eabc6138144735