Modernize the "codecs" feature

Change-Id: Idee19112581bff64a2e0b8e331dd3d779aca165b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

src/corelib/codecs/codecs.pri

@@ -1,22 +1,28 @@
 # Qt core library codecs module
 
 HEADERS += \
-    codecs/qisciicodec_p.h \
     codecs/qlatincodec_p.h \
     codecs/qsimplecodec_p.h \
     codecs/qtextcodec_p.h \
     codecs/qtextcodec.h \
-    codecs/qtsciicodec_p.h \
     codecs/qutfcodec_p.h
 
 SOURCES += \
-    codecs/qisciicodec.cpp \
     codecs/qlatincodec.cpp \
     codecs/qsimplecodec.cpp \
     codecs/qtextcodec.cpp \
-    codecs/qtsciicodec.cpp \
     codecs/qutfcodec.cpp
 
+qtConfig(codecs) {
+    HEADERS += \
+        codecs/qisciicodec_p.h \
+        codecs/qtsciicodec_p.h
+
+    SOURCES += \
+        codecs/qisciicodec.cpp \
+        codecs/qtsciicodec.cpp
+}
+
 qtConfig(icu) {
     HEADERS += \
         codecs/qicucodec_p.h

src/corelib/codecs/qicucodec.cpp

@@ -373,7 +373,7 @@ static QTextCodec *loadQtCodec(const char *name)
         return new QUtf32LECodec;
     if (!strcmp(name, "ISO-8859-16") || !strcmp(name, "latin10") || !strcmp(name, "iso-ir-226"))
         return new QSimpleTextCodec(13 /* == 8859-16*/);
-#ifndef QT_NO_CODECS
+#if QT_CONFIG(codecs)
     if (!strcmp(name, "TSCII"))
         return new QTsciiCodec;
     if (!qstrnicmp(name, "iscii", 5))

src/corelib/codecs/qisciicodec.cpp

@@ -40,8 +40,6 @@
 #include "qtextcodec_p.h"
 #include "qlist.h"
 
-#ifndef QT_NO_CODECS
-
 QT_BEGIN_NAMESPACE
 
 /*!
@@ -291,5 +289,3 @@ QString QIsciiCodec::convertToUnicode(const char* chars, int len, ConverterState
 }
 
 QT_END_NAMESPACE
-
-#endif // QT_NO_CODECS

src/corelib/codecs/qisciicodec_p.h

@@ -54,9 +54,9 @@
 #include <QtCore/private/qglobal_p.h>
 #include "QtCore/qtextcodec.h"
 
-QT_BEGIN_NAMESPACE
+QT_REQUIRE_CONFIG(codecs);
 
-#ifndef QT_NO_CODECS
+QT_BEGIN_NAMESPACE
 
 class QIsciiCodec : public QTextCodec {
 public:
@@ -75,8 +75,6 @@ private:
     int idx;
 };
 
-#endif // QT_NO_CODECS
-
 QT_END_NAMESPACE
 
 #endif // QISCIICODEC_P_H

src/corelib/codecs/qtextcodec.cpp

@@ -57,8 +57,10 @@
 #include "qlatincodec_p.h"
 
 #if !defined(QT_BOOTSTRAPPED)
+#if QT_CONFIG(codecs)
 #  include "qtsciicodec_p.h"
 #  include "qisciicodec_p.h"
+#endif
 #if QT_CONFIG(icu)
 #include "qicucodec_p.h"
 #else
@@ -268,7 +270,7 @@ static void setup()
         return;
     initialized = true;
 
-#if !defined(QT_NO_CODECS) && !defined(QT_BOOTSTRAPPED)
+#if QT_CONFIG(codecs) && !defined(QT_BOOTSTRAPPED)
     (void)new QTsciiCodec;
     for (int i = 0; i < 9; ++i)
         (void)new QIsciiCodec(i);
@@ -293,7 +295,7 @@ static void setup()
 #if defined(Q_OS_WIN32)
     (void) new QWindowsLocalCodec;
 #endif // Q_OS_WIN32
-#endif // !QT_NO_CODECS && !QT_BOOTSTRAPPED
+#endif // codecs && !QT_BOOTSTRAPPED
 
     (void)new QUtf16Codec;
     (void)new QUtf16BECodec;

src/corelib/codecs/qtsciicodec.cpp

@@ -44,8 +44,6 @@
 #include "qtsciicodec_p.h"
 #include "qlist.h"
 
-#ifndef QT_NO_CODECS
-
 QT_BEGIN_NAMESPACE
 
 static unsigned char qt_UnicodeToTSCII(ushort u1, ushort u2, ushort u3);
@@ -493,5 +491,3 @@ static unsigned int qt_TSCIIToUnicode(uint code, uint *s)
 }
 
 QT_END_NAMESPACE
-
-#endif // QT_NO_CODECS

src/corelib/codecs/qtsciicodec_p.h

@@ -83,9 +83,9 @@
 #include <QtCore/private/qglobal_p.h>
 #include "QtCore/qtextcodec.h"
 
-QT_BEGIN_NAMESPACE
+QT_REQUIRE_CONFIG(codecs);
 
-#ifndef QT_NO_CODECS
+QT_BEGIN_NAMESPACE
 
 class QTsciiCodec : public QTextCodec {
 public:
@@ -98,8 +98,6 @@ public:
     QByteArray convertFromUnicode(const QChar *, int, ConverterState *) const override;
 };
 
-#endif // QT_NO_CODECS
-
 QT_END_NAMESPACE
 
 #endif // QTSCIICODEC_P_H

src/corelib/global/qconfig-bootstrapped.h

@@ -130,7 +130,6 @@
 #define QT_NO_TEXTCODEC
 #define QT_FEATURE_textcodec -1
 #else
-#define QT_NO_CODECS
 #define QT_FEATURE_codecs -1
 #define QT_FEATURE_commandlineparser 1
 #define QT_FEATURE_textcodec 1