ICU-22687 Fix genren.pl not to skip C++ functions on Mac #47

Job	Run time
clang-valgrind-test	9m 49s
clang-valgrind-intltest (utility)	6m 32s
clang-valgrind-intltest (normalize)	6m 44s
clang-valgrind-intltest (collator)	4m 57s
clang-valgrind-intltest (regex)	5m 29s
clang-valgrind-intltest (format)	17m 4s
clang-valgrind-intltest (translit)	5m 50s
clang-valgrind-intltest (rbbi)	6m 52s
clang-valgrind-intltest (rbnf)	5m 54s
clang-valgrind-intltest (rbnfrt)	6m 20s
clang-valgrind-intltest (icuserv)	5m 8s
clang-valgrind-intltest (idna)	5m 4s
clang-valgrind-intltest (convert)	6m 23s
clang-valgrind-intltest (rbnfp)	5m 25s
clang-valgrind-intltest (csdet)	4m 40s
clang-valgrind-intltest (spoof)	5m 5s
clang-valgrind-intltest (bidi)	5m 2s
	1h 52m 18s

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