libunwind: use latest release v1.6.2 as a base

Now we base on some unreleased state of libunwind. This is by itself not
a good practice. Yet the main motivation is that in the current version of
libunwind fast path for backtrace detection on x86_64 does not work.
I guess this is because of libunwind/libunwind@400b3f819ad4 (" x86_64: Stop
aliasing RSP and CFA"). See libunwind/libunwind#440. Fortunately this
commit is not present it the latest release.

Using fast or slow path has a great impact on performance of debug build
where collecting fiber gc allocation backtrace is turned on by default.
It surely depends on frequency and pattern of allocation. Test
sql/delete3 depends on backtrace performance most dramatically. On some
installations collecting backtraces slowed down the test up to 10 times.

If fast path is available then collecting backtrace does not affect
performance in a noticeable way.

I propose not to keep autotools products in the libunwind fork repo as
it is done previously. LOG_CONFIGURE is removed because it somehow
incompatible with using && in CONFIGURE_COMMAND command and not critical
to the build.

Also add autotools build dependencies for packpack package specs.
Currently not all packpack images have autotools preinstalled so this is
required for build to success. Anyway we'b better have precise build
requirements in build specs.

Follow-up #5665

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