ICU-22714 fix zos build, use OpenXL #2865

Job	Run time
clang-valgrind-intltest (utility)	6m 43s
clang-valgrind-test	10m 23s
clang-valgrind-intltest (normalize)	6m 16s
clang-valgrind-intltest (collator)	5m 7s
clang-valgrind-intltest (regex)	5m 45s
clang-valgrind-intltest (format)	16m 29s
clang-valgrind-intltest (translit)	5m 48s
clang-valgrind-intltest (rbbi)	7m 44s
clang-valgrind-intltest (rbnf)	6m 11s
clang-valgrind-intltest (rbnfrt)	6m 8s
clang-valgrind-intltest (icuserv)	5m 44s
clang-valgrind-intltest (idna)	5m 19s
clang-valgrind-intltest (convert)	6m 57s
clang-valgrind-intltest (rbnfp)	5m 10s
clang-valgrind-intltest (csdet)	5m 40s
clang-valgrind-intltest (spoof)	5m 6s
clang-valgrind-intltest (bidi)	5m 51s
	1h 56m 21s

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