doc: Fix three "Cannot tie" errors

Two of the three functions were for functions that
should not be documented. The third was a function
protected by #ifndef Q_OS_DARWIN, which required a
test of Q_CLANG_QDOC in the header and cpp files.

Change-Id: Id2ab3e4f2ea896dc628a622de2e80a19c18eb9fe
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

src/corelib/kernel/qmetaobject.cpp

@@ -1341,7 +1341,7 @@ QByteArray QMetaObject::normalizedSignature(const char *method)
 
 enum { MaximumParamCount = 11 }; // up to 10 arguments + 1 return value
 
-/*!
+/*
     Returns the signatures of all methods whose name matches \a nonExistentMember,
     or an empty QByteArray if there are no matches.
 */

src/corelib/kernel/qtranslator.cpp

@@ -1064,7 +1064,7 @@ searchDependencies:
     return QString();
 }
 
-/*!
+/*
     Empties this translator of all contents.
 
     This function works with stripped translator files.

src/corelib/tools/qhash.cpp

@@ -963,7 +963,7 @@ uint qHash(double key, uint seed) Q_DECL_NOTHROW
     return key != 0.0  ? hash(reinterpret_cast<const uchar *>(&key), sizeof(key), seed) : seed ;
 }
 
-#ifndef Q_OS_DARWIN
+#if !defined(Q_OS_DARWIN) || defined(Q_CLANG_QDOC)
 /*! \relates QHash
     \since 5.3
 

src/corelib/tools/qhashfunctions.h

@@ -90,7 +90,7 @@ Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(quint64 key, uint seed
 Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(qint64 key, uint seed = 0) Q_DECL_NOTHROW { return qHash(quint64(key), seed); }
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(float key, uint seed = 0) Q_DECL_NOTHROW;
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(double key, uint seed = 0) Q_DECL_NOTHROW;
-#ifndef Q_OS_DARWIN
+#if !defined(Q_OS_DARWIN) || defined(Q_CLANG_QDOC)
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(long double key, uint seed = 0) Q_DECL_NOTHROW;
 #endif
 Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(const QChar key, uint seed = 0) Q_DECL_NOTHROW { return qHash(key.unicode(), seed); }