i18npool: remove versioned ICU forward declarations

(regression from c6b7f555)

i18npool/IwyuFilter_i18npool.yaml

 ---
 assumeFilename: i18npool/source/localedata/localedata.cxx
 blacklist:
+    i18npool/inc/breakiterator_unicode.hxx:
+    # contains versioned namespace so cannot forward declare
+    - unicode/brkiter.h
     i18npool/inc/breakiteratorImpl.hxx:
     # Base class needs complete type
     - com/sun/star/i18n/XBreakIterator.hpp
@@ -84,6 +87,8 @@ blacklist:
     # Base class needs complete type
     - com/sun/star/util/XTextSearch2.hpp
     - com/sun/star/lang/XServiceInfo.hpp
+    # contains versioned namespace so cannot forward declare
+    - unicode/regex.h
     i18npool/source/breakiterator/xdictionary.cxx:
     # Used after #ifdef DICT_JA_ZH_IN_DATAFILE
     - config_folders.h

i18npool/inc/breakiterator_unicode.hxx

@@ -21,12 +21,11 @@
 
 #include "breakiteratorImpl.hxx"
 
+#include <unicode/brkiter.h>
 #include <unicode/utext.h>
 #include <memory>
 #include <unordered_map>
 
-namespace icu_63 { class BreakIterator; }
-
 namespace i18npool {
 
 #define LOAD_CHARACTER_BREAKITERATOR    0

i18npool/source/search/textsearch.hxx

@@ -27,6 +27,7 @@
 #include <map>
 #include <memory>
 
+#include <unicode/regex.h>
 #include <unicode/unistr.h>
 #include <unicode/uversion.h>
 
@@ -34,7 +35,6 @@ namespace com::sun::star::i18n { class XBreakIterator; }
 namespace com::sun::star::i18n { class XCharacterClassification; }
 namespace com::sun::star::i18n { class XExtendedTransliteration; }
 namespace com::sun::star::uno { class XComponentContext; }
-namespace icu_63 { class RegexMatcher; }
 
 
 using namespace U_ICU_NAMESPACE;