ICU-22326 Fix build problems

See #2685

icu4c/source/test/depstest/dependencies.txt

@@ -145,6 +145,7 @@ group: iostream
     "std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)"
     std::ios_base::Init::Init()
     std::ios_base::Init::~Init()
+    std::ios_base_library_init()
     std::istream::get()
     std::istream::putback(char)
     # Additional symbols in an optimized build.

icu4c/source/test/fuzzer/locale_util.h

@@ -4,6 +4,7 @@
 #ifndef I18N_ICU_FUZZ_LOCALE_UTIL_H_
 #define I18N_ICU_FUZZ_LOCALE_UTIL_H_
 
+#include <cstdint>
 #include <string>
 
 // Takes uint8_t data from fuzzer, and makes a zero terminated string.