python3-pyelftools: Add DWARF-5 support

python3-pyelftools 0.26 can't handle DWARF-5, which is generated by default
by modern toolchains (clang 12+, gcc 11+).

Update it to 0.27 with an extra patch taken from upstream git to support
DWARF-5 so we can use it (e.g. in the Zephyr kernel test suite) without
switching the toolchains back to DWARF-4.

Signed-off-by: Bernhard Rosenkränzer <bernhard.rosenkraenzer.ext@huawei.com>