Work around an apparent gcc optimizer bug in wxClassInfo

Rewrite a complex expression in wxClassInfo::IsKindOf() as several statements
to avoid what looks like a gcc optimizer bug as it was dereferencing
m_baseInfo1 pointer even when it was null.

The new version is not completely equivalent to the old one as it doesn't
check for info == NULL which is not really necessary, but this is just a side
effect and doesn't affect anything, the important change is avoiding doing
everything in a single expression.

Closes #17483.

include/wx/rtti.h

@@ -85,10 +85,22 @@ public:
 
     bool IsKindOf(const wxClassInfo *info) const
     {
-        return info != 0 &&
-               ( info == this ||
-                 ( m_baseInfo1 && m_baseInfo1->IsKindOf(info) ) ||
-                 ( m_baseInfo2 && m_baseInfo2->IsKindOf(info) ) );
+        if ( info == this )
+            return true;
+
+        if ( m_baseInfo1 )
+        {
+            if ( m_baseInfo1->IsKindOf(info) )
+                return true;
+        }
+
+        if ( m_baseInfo2 )
+        {
+            if ( m_baseInfo2->IsKindOf(info) )
+                return true;
+        }
+
+        return false;
     }
 
     wxDECLARE_CLASS_INFO_ITERATORS();