[icu] Support loading data file from default location

src/icu_util.h

Index: src/icu_util.h
diff --git a/src/icu_util.h b/src/icu_util.h
index c308decfe5f63dba0e4927a83b6bf1951be26a79..c5ef862f515ebdfd3794d4674c4db5d4063c0431 100644
--- a/src/icu_util.h
+++ b/src/icu_util.h
@@ -14,6 +14,11 @@ namespace internal {
 // function should be called before ICU is used.
 bool InitializeICU(const char* icu_data_file);
 
+// Like above, but using the default icudtl.dat location if icu_data_file is
+// not specified.
+bool InitializeICUDefaultLocation(const char* exec_path,
+                                  const char* icu_data_file);
+
 }  // namespace internal
 }  // namespace v8