Don't try to evaluate value of value-dependent Expr

...which causes asserts to fire since <https://github.com/llvm/llvm-project/
commit/04323c24a1ac9464471331d9f6499d3cb95d1ccd> "Added an assertion to constant
evaluation enty points that prohibits …"

Change-Id: Iafbf1cea85d15a38a71275d4cea8303bab500f6a
Reviewed-on: https://gerrit.libreoffice.org/72723
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/empty.cxx

@@ -100,7 +100,7 @@ private:
             return;
         }
         APSInt val;
-        if (!rhs->isIntegerConstantExpr(val, compiler.getASTContext()))
+        if (rhs->isValueDependent() || !rhs->isIntegerConstantExpr(val, compiler.getASTContext()))
         {
             return;
         }

compilerplugins/clang/expressionalwayszero.cxx

@@ -135,7 +135,7 @@ std::unique_ptr<APSInt> ExpressionAlwaysZero::getExprValue(Expr const * expr)
         return std::unique_ptr<APSInt>();
     }
     APSInt x1;
-    if (compat::EvaluateAsInt(expr, x1, compiler.getASTContext()))
+    if (!expr->isValueDependent() && compat::EvaluateAsInt(expr, x1, compiler.getASTContext()))
         return std::unique_ptr<APSInt>(new APSInt(x1));
     return std::unique_ptr<APSInt>();
 }