util/util.c: adding an error printer

+ no return value should go ignored
util/util.c: remove color lib dependency
gammaray: migrate from f* family to lower level IO functions

+ Examples: fopen --> open,
            fseeko --> lseek64,
            fread --> read,
            fwrite --> write,
            fclose --> close

+ This should fix Android builds (do not currently respect #define _FILE_OFFSET_BITS 64)

+ ext4 has been tested for regressions (gray-crawler work cycle)

- gray-inferencer, gray-ndb-queuer, gray-fs still need testing
- ntfs untested anywhere
nbd/nbd.c: safer handling of lssek64 return values
Merge pull request #32 from cmusatyalab/safe-64bit-crawler

Safe 64bit crawler