bzip2: block size 9 -> 5, reduces memory by 400Kbytes, doesn't affect speed
or compression ratio on all but the largest bytecode files (>1MB)
zip: level 9 -> 6, this speeds up compression time by ~30% but only
degrades the compressed size by a few bytes per megabyte. Those few
bytes aren't worth the effort.
llvm-svn: 17647
previously temporary NULLCOMP implementation that merely copies the data
verbatim without compression. Also, don't warn if there's no compression
library as that is taken care of during configuration time.
llvm-svn: 16654
