bug#16586: grep: infinite loop in grep -P on some files with invalid UTF-8 sequences

[Paul Eggert]

For what it's worth I can't reproduce this bug on Fedora 20 x86-64, even 
with valgrind and/or GCC -faddress=sanitize.  I'm using Fedora 
pcre-8.33-4.fc20.x86_64.