Warning when compiled under Cygwin

[AdrianSimionov]

When compiling under Cygwin on Windows 7, following warning is generated:

./.libs/lt-docsis.c: In function 'lt_fatal': ./.libs/lt-docsis.c:593:1: warning: function might be candidate for attribute 'noreturn' [-Wsuggest-attribute=noreturn] lt_fatal (const char *file, int line, const char *message, ...) ^