Fixed several Clang compile warnings and a few potential bugs.

src/lib-sieve/rfc2822.h

src/lib-sieve/sieve-binary-dumper.c

src/lib-sieve/sieve-binary-dumper.h

src/lib-sieve/sieve-error.c

src/lib-sieve/sieve-result.h

src/lib-sieve/sieve-runtime-trace.c

src/lib-sieve/sieve-runtime-trace.h

src/lib-sievestorage/sieve-storage.c

src/testsuite/testsuite-log.c