doc: Prevent overwrite of qbytearray.html

A use of Q_GLOBAL_STATIC() tricked clangqdoc into
thinking it created something called QByteArray that
should be documented, so the html generator tried to
overwrite qbytearray.html which had already been
created for the real QByteArray. This probably means
there is a bug in the clang visitor class, but I can't
see it, and this change eliminates 4 qdoc errors.

Change-Id: Iee333217212ce60727cd9424a19b8e96a20547b4
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/corelib/kernel/qfunctions_fake_env_p.h

@@ -77,7 +77,9 @@ struct NameEquals {
     { return qstrcmp(other.name, name) == 0; }
 };
 
+#ifndef Q_CLANG_QDOC
 Q_GLOBAL_STATIC(QVector<Variable>, qt_app_environment)
+#endif
 
 errno_t qt_fake_getenv_s(size_t *sizeNeeded, char *buffer, size_t bufferSize, const char *varName)
 {