srecord: update 1.63 -> 1.64

libgcrypt was an optional dependency in previous versions too, but in
this version the build fails unless libgcrypt is there, or
--without-gcrypt is passed to configure.

Since libgcrypt only increases the closure size from 131 MiB to 136 MiB,
I'm adding it as a dependency.

[1]: http://srecord.sourceforge.net/change_log.txt