[ClamAV] Build script improvements (#2102)
[ClamAV] Build script improvements (#2102)

Build script improvements to use the WORK dir, rather than polluting the SRC dir, and to use make in the clamav-devel/fuzz directory rather than building source files manually. 
FeliciaLim/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,FeliciaLim/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,google/oss-fuzz,google/oss-fuzz,FeliciaLim/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,FeliciaLim/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz,googlefonts/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,FeliciaLim/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,googlefonts/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,googlefonts/oss-fuzz