gpgscm: Add and use opcode for reversing a list in place.
* tests/gpgscm/lib.scm (string-split-pln): Use 'reverse!'. (string-rtrim): Likewise. * tests/gpgscm/opdefines.h (reverse!): New opcode. * tests/gpgscm/scheme.c (opexe_0): Handle new opcode.
- Signed-off-by: Justus Winter <justus@g10code.com>