Use some more O3TL_UNREACHABLE

Change-Id: Ibcf1b1de7b43460266e99fc9f27c1de0b510a361
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/136779
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

ucbhelper/source/client/content.cxx

@@ -1022,8 +1022,6 @@ bool Content::isFolder()
 }
 
 
-SAL_WNOUNREACHABLE_CODE_PUSH
-
 bool Content::isDocument()
 {
     bool bDoc = false;
@@ -1037,13 +1035,9 @@ bool Content::isDocument()
                     get() ) ),
          m_xImpl->getEnvironment() );
 
-    // Unreachable - cancelCommandExecution always throws an exception,
-    // But some compilers complain...
-    return false;
+    O3TL_UNREACHABLE;
 }
 
-SAL_WNOUNREACHABLE_CODE_POP
-
 void Content::lock()
 {
     Command aCommand;