Removed unecessary jump after commands like stop.

sieve/examples/vivil.sieve

sieve/tests/stop.sieve

src/lib-sieve/cmd-if.c

src/lib-sieve/sieve-commands.c

src/lib-sieve/sieve-commands.h

src/lib-sieve/sieve-generator.c

src/lib-sieve/sieve-generator.h