[PATCH] Fix for Squid 3.4.5 segfault

Squid 3.4.5 segfaults when formatting log lines for me. It looks like
this is down to fmt->data.timespec being uninitialised, and affects the
%tg format specifier.

As far as I can tell, fmt->data.timespec is never set anywhere, and we
should probably be using fmt->data.string instead.

The attached patch removes timespec, fixing the segmentation fault.

I can't see any relevant code change between 3.4.4 and 3.4.5, so I'm
guessing this may be down to the toolchain change. Presumably the
compiler used to initialise the pointer to NULL and nolonger does.

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