qdoc: Define Q_COMPILER_UNICODE_STRINGS

Some public functions in QString and QDebug are declared inside
Q_COMPILER_UNICODE_STRINGS. This commit defines it for QDoc, and
adds documentation for QDebug functions that are now visible to
QDoc.

Change-Id: Ia7f2501c1dc7b8244dcc3ce4adcd2019fdbffcb6
Reviewed-by: Martin Smith <martin.smith@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

doc/global/qt-cpp-defines.qdocconf

@@ -14,6 +14,7 @@ defines                 += Q_QDOC \
                           Q_NO_USING_KEYWORD \
                           __cplusplus \
                           Q_COMPILER_INITIALIZER_LISTS \
+                          Q_COMPILER_UNICODE_STRINGS \
                           Q_COMPILER_UNIFORM_INIT \
                           Q_COMPILER_RVALUE_REFS
 

src/corelib/io/qdebug.cpp

@@ -578,6 +578,22 @@ QDebug &QDebug::resetFormat()
     output, but note that some QDebug backends might not be 8-bit clean.
 */
 
+/*!
+    \fn QDebug &QDebug::operator<<(char16_t t)
+    \since 5.5
+
+    Writes the UTF-16 character, \a t, to the stream and returns a reference
+    to the stream.
+*/
+
+/*!
+    \fn QDebug &QDebug::operator<<(char32_t t)
+    \since 5.5
+
+    Writes the UTF-32 character, \a t, to the stream and returns a reference
+    to the stream.
+*/
+
 /*!
     \fn QDebug &QDebug::operator<<(const QString &s)