doc: Don't let qdoc see some defines that cause trouble

This update surrounds some #defines with #ifndef Q_CLANG_QDOC
because they define some names that conflict with formal parameter
names. Otherwise, clang starts replacing formal parameter names
with $27 etc, when qdoc runs, and that causes trouble for qdoc.
The change also replaces one use of Q_QDOC with Q_CLANG_QDOC.

Change-Id: I6e93bf1e0d30d7590280b6f18f0e694556050685
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

src/gui/kernel/qkeysequence.h

@@ -59,7 +59,7 @@ Q_GUI_EXPORT QDataStream &operator<<(QDataStream &in, const QKeySequence &ks);
 Q_GUI_EXPORT QDataStream &operator>>(QDataStream &out, QKeySequence &ks);
 #endif
 
-#ifdef Q_QDOC
+#ifdef Q_CLANG_QDOC
 void qt_set_sequence_auto_mnemonic(bool b);
 #endif
 

src/gui/painting/qt_mips_asm_dsp_p.h

@@ -55,6 +55,7 @@
 #pragma qt_sync_stop_processing
 #endif
 
+#ifndef Q_CLANG_QDOC
 #define zero $0
 #define AT   $1
 #define v0   $2
@@ -88,6 +89,7 @@
 #define fp   $30
 #define s8   $30
 #define ra   $31
+#endif
 
 /*
  * LEAF_MIPS32R2 - declare leaf_mips32r2 routine