[tlbuild] New ICU tests fail on aarch64-linux (on Debian 10)

[ttk at t-lab.opal.ne.jp]

Dear Johannes,

Thank you for your deep examination.
> What I could do is to compare the content of the rules string as
> created by unescape(). There *is* a difference:
> Note the one extra byte at the beginning. Smells like the reason why
> ucol_openRules() complains. And what is in this byte, appears
> platform-dependent, or worse. Uninitialised variable? Index out of
> bounds? But why is the *length* compiler dependent?

I guess it is due to uninitialized string "rules[]".
I committed r60139 to fix it.

Best,
Takuji