convert some plugins to use the sharedplugin infrastructure

Change-Id: I690d9df436abdadc51a6d3f7df686a2e37f79f73
Reviewed-on: https://gerrit.libreoffice.org/75624
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

compilerplugins/clang/stringconstant.cxx

@@ -7,6 +7,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
+#ifndef LO_CLANG_SHARED_PLUGINS
+
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
@@ -108,6 +110,8 @@ public:
     explicit StringConstant(loplugin::InstantiationData const & data):
         FilteringRewritePlugin(data) {}
 
+    bool preRun() override;
+
     void run() override;
 
     bool TraverseCallExpr(CallExpr * expr);
@@ -186,14 +190,15 @@ private:
     std::stack<Expr const *> calls_;
 };
 
-void StringConstant::run() {
-    if (compiler.getLangOpts().CPlusPlus
+bool StringConstant::preRun() {
+    return compiler.getLangOpts().CPlusPlus
         && compiler.getPreprocessor().getIdentifierInfo(
-            "LIBO_INTERNAL_ONLY")->hasMacroDefinition())
+            "LIBO_INTERNAL_ONLY")->hasMacroDefinition();
             //TODO: some parts of it are useful for external code, too
-    {
+}
+void StringConstant::run() {
+    if (preRun())
         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
-    }
 }
 
 bool StringConstant::TraverseCallExpr(CallExpr * expr) {
@@ -2087,8 +2092,10 @@ void StringConstant::handleFunArgOstring(
     }
 }
 
-loplugin::Plugin::Registration< StringConstant > X("stringconstant", true);
+loplugin::Plugin::Registration< StringConstant > stringconstant("stringconstant");
 
-}
+} // namespace
+
+#endif // LO_CLANG_SHARED_PLUGINS
 
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