lib/icu/CaseFold: remove Windows implementation

Reverts commit fb3564fbe7

LCMapStringEx() doesn't do what I imagined it would do 5 years ago.
D'oh!

Closes https://github.com/MusicPlayerDaemon/MPD/issues/820

NEWS

@@ -6,6 +6,8 @@ ver 0.21.23 (not yet released)
   - alsa: implement channel mapping for 5.0 and 7.0
 * player
   - drain outputs at end of song in "single" mode
+* Windows
+  - fix case insensitive search
 
 ver 0.21.22 (2020/04/02)
 * database

src/lib/icu/CaseFold.cxx

@@ -36,11 +36,6 @@
 #include <ctype.h>
 #endif
 
-#ifdef _WIN32
-#include "Win32.hxx"
-#include <windows.h>
-#endif
-
 #include <memory>
 
 #include <assert.h>
@@ -72,25 +67,6 @@ try {
 	folded.SetSize(folded_length);
 	return UCharToUTF8({folded.begin(), folded.size()});
 
-#elif defined(_WIN32)
-	const auto u = MultiByteToWideChar(CP_UTF8, src);
-
-	const int size = LCMapStringEx(LOCALE_NAME_INVARIANT,
-				       LCMAP_SORTKEY|LINGUISTIC_IGNORECASE,
-				       u.c_str(), -1, nullptr, 0,
-				       nullptr, nullptr, 0);
-	if (size <= 0)
-		return AllocatedString<>::Duplicate(src);
-
-	std::unique_ptr<wchar_t[]> buffer(new wchar_t[size]);
-	if (LCMapStringEx(LOCALE_NAME_INVARIANT,
-			  LCMAP_SORTKEY|LINGUISTIC_IGNORECASE,
-			  u.c_str(), -1, buffer.get(), size,
-			  nullptr, nullptr, 0) <= 0)
-		return AllocatedString<>::Duplicate(src);
-
-	return WideCharToMultiByte(CP_UTF8, buffer.get());
-
 #else
 #error not implemented
 #endif

src/lib/icu/CaseFold.hxx

@@ -22,7 +22,7 @@
 
 #include "config.h"
 
-#if defined(HAVE_ICU) || defined(_WIN32)
+#ifdef HAVE_ICU
 #define HAVE_ICU_CASE_FOLD
 
 #include "util/Compiler.h"