Update configure based on b90f1baa.
Merge pull request #42 from seanbright/update-configure

Update configure based on b90f1baa.
- fixed read of memory out of 'seq' variable bounds
- fixed AEAD IV calculation for big-endian machines
Merge pull request #43 from ukreator/master

Memory access fixes.  Thanks for contributing this fix.
This commit resolves issue #46.  The GCM mode was using the wrong master SALT length.  The master SALT should be 96 bits instead of 112 bits.  Note, GCM mode uses the legacy CTR mode for the KDF.  The legagacy CTR mode cipher implementations assume a 112 bit SALT.  Changes to the cipher abstraction layer API are required to provide the ability to specify the SALT length.  For now this commit modifies the SRTP layer to ensure the SALT is zero-appended before initializing the KDF.  This commit also provides public definitions for the GCM cipher suite master key sizes to avoid confusion for application developers.
Set the algorithm member on cipher_t when allocating AES crypto instance.  Apply same fix to NULL cipher.