[BioC] affyio install deps

[Caroline Johnston]

Hi,

With R 2.6.2 on Ubuntu Gutsy affyio install (via biocLite.R) fails.
apt-get install zlib1g-dev seems to fix it, but this isn't immediately
obvious from the error message:

...load of fread_functions errors...
make: *** [fread_functions.o] Error 1
chmod: cannot access `/usr/local/lib/R/library/affyio/libs/*': No such 
file or directory

Sorry if you already know about this. Just thought it might save someone 
else ten mins of faffing about.

Cheers,
Cass xx