Bug in _add_priority adds duplicates and unwanted algorithms.

[Tim Kosse]

Hi,

when setting a priority string of SECURE256:+SECURE128, I noticed that on some 
platforms, 3DES was included in the list of ciphers, but is lacking on most 
platforms. Notably, MinGW cross-compiles with -O2 are affected.

The problem is in _add_priority in gnutls_priority.c, where the continue 
statement in the inner loop should have instead returned to the beginning of 
the outer loop. The result is that ciphers are added multiple times and 
depending what$

These two patches fix the problem and also enable the print-ciphersuites 
example to be built by default.

Regards,
Tim Kosse