corelib: settings - make qsettings.cpp unity buildable

Both qsettings.cpp and qjsonparser.cpp defined Space in the
global namespace. Hiding it in one of them in an implementation
namespace resolves the name clash.

Pick-to: 6.6 6.5
Change-Id: I8dd1244f80d87f3908597ed82c8e41b49b7b916c
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit 4ff65f0e5615b1132ec13c6eeba3647162d8dd0f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/CMakeLists.txt

@@ -327,7 +327,6 @@ qt_internal_add_module(Core
         text/qstringconverter.cpp # enum Data
         tools/qcryptographichash.cpp # KeccakNISTInterface/Final
         io/qdebug.cpp # undef qDebug
-        io/qsettings.cpp # Space (also in qjsonparser.cpp)
     NO_PCH_SOURCES
         compat/removed_api.cpp
         global/qsimd.cpp

src/corelib/io/qsettings.cpp

@@ -1518,6 +1518,8 @@ void QConfFileSettingsPrivate::syncConfFile(QConfFile *confFile)
     }
 }
 
+namespace SettingsImpl {
+
 enum { Space = 0x1, Special = 0x2 };
 
 static const char charTraits[256] =
@@ -1544,10 +1546,15 @@ static const char charTraits[256] =
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 };
 
+} // namespace SettingsImpl
+
+using SettingsImpl::charTraits;
+
 bool QConfFileSettingsPrivate::readIniLine(QByteArrayView data, qsizetype &dataPos,
                                            qsizetype &lineStart, qsizetype &lineLen,
                                            qsizetype &equalsPos)
 {
+    using namespace SettingsImpl;
     qsizetype dataLen = data.size();
     bool inQuotes = false;