All symmetric cipher algorithms and hash algorithms now include support
for a POLARSSL_XXX_ALT flag that prevents the definition of the
algorithm context structure and all 'core' functions.
(cherry picked from commit 4087c47043cb7b8b51e69f1de47ab6a2bccead3d)
New padding checking is unbiased on correct or incorrect padding and
has no branch prediction timing differences.
The additional MAC checks further straighten out the timing differences.
- As a consequence all error code that were positive were changed. A lot of MALLOC_FAILED and FILE_IO_ERROR error codes added for different modules.
- Programs and tests were adapted accordingly
