fix a new warning for gcc 4.6.3

  src/carp_tokenizer.c: In function ‘file_read’:
  src/carp_tokenizer.c:86:8: error: ignoring return value of ‘fread’, declared with attribute warn_unused_result [-Werror=unused-result]
Merge branch 'master' of https://github.com/tekknolagi/carp
macros!
Merge branch 'master' of https://github.com/akkartik/carp - assert for
file read