Fixed a few warnings.

Rev: src/cpp.c:1.68
Rev: src/modules/Image/encodings/png.c:1.36
Rev: src/modules/Image/encodings/tga.c:1.19
Rev: src/modules/_Crypto/crypto.c:1.35
Rev: src/modules/_Crypto/des.c:1.17
Rev: src/modules/_Crypto/idea.c:1.15
Rev: src/modules/_Crypto/invert.c:1.10
Rev: src/modules/_Crypto/md2.c:1.9
Rev: src/modules/_Crypto/md5.c:1.14
Rev: src/modules/_Crypto/nt.c:1.4
Rev: src/modules/_Crypto/sha.c:1.17
Rev: src/modules/spider/spider.c:1.95
Rev: src/modules/spider/stardate.c:1.10
Rev: src/modules/spider/xml.c:1.24
Rev: src/opcodes.c:1.80
Rev: src/preprocessor.h:1.27