ext/intl: level up c++ runtime std for icu 74 and onwards.

[devnexen]

to align with what is required to build icu 74 itself.

[petk]

Suggested change

	AC_RUN_IFELSE([AC_LANG_SOURCE([[
	#include <unicode/uvernum.h>
	int main(int argc, char *argv[])
	{
	#if U_ICU_VERSION_MAJOR_NUM >= 74
	return 0;
	#else
	return 1;
	#endif
	}
	]])],[
	AC_MSG_RESULT([yes])
	PHP_CXX_COMPILE_STDCXX(17, mandatory, PHP_INTL_STDCXX)
	],[
	AC_MSG_RESULT([no])
	PHP_CXX_COMPILE_STDCXX(11, mandatory, PHP_INTL_STDCXX)
	], [
	])
	AS_IF([test "$PKG_CONFIG icu-uc --atleast-version=74"],[
	AC_MSG_RESULT([yes])
	PHP_CXX_COMPILE_STDCXX(17, mandatory, PHP_INTL_STDCXX)
	],[
	AC_MSG_RESULT([no])
	PHP_CXX_COMPILE_STDCXX(11, mandatory, PHP_INTL_STDCXX)
	])

Perhaps instead of running the test program, this can be checked directly from the package.

Otherwise, also something like this can be done:

AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <unicode/uvernum.h>],[[
  #if U_ICU_VERSION_MAJOR_NUM >= 74
    return 0;
  #else
  # error "ICU version < 74"
  #endif
]])],[
  AC_MSG_RESULT([yes])
  PHP_CXX_COMPILE_STDCXX(17, mandatory, PHP_INTL_STDCXX)
],[
  AC_MSG_RESULT([no])
  PHP_CXX_COMPILE_STDCXX(11, mandatory, PHP_INTL_STDCXX)
])

[devnexen]

ping :)