Squelch a warning in pcap_open_offline_with_tstamp_precision().

Clang 10.0.1 on NetBSD 9.2 and OpenBSD 6.9:

./savefile.c:354:4: warning: code will never be executed
  [-Wunreachable-code]

In Linux, for example, stdin is a pointer to FILE, so it can be NULL or
non-NULL. In NetBSD and OpenBSD it is a macro:

 #define stdin   (&__sF[0])

By definition, address of a variable is never NULL hence the warning.
However, assigning the address to a pointer and then immediately
comparing the pointer with NULL is not a condition that is always false,
as far as Clang sees it. Apply the workaround and remove two exemption
rules from build.sh.

0 files changed, 0 insertions, 0 deletions