Fix -Wpedantic on std::process.

src/V3LinkDot.cpp

@@ -1711,7 +1711,8 @@ private:
     }
     void visit(AstTypedefFwd* nodep) override {
         VSymEnt* const foundp = m_statep->getNodeSym(nodep)->findIdFallback(nodep->name());
-        if (!foundp && v3Global.opt.pedantic()) {
+        if (!foundp && v3Global.opt.pedantic()
+            && nodep->name() != "process") {  // Process is dangling as isn't implemented yet
             // We only check it was ever really defined in pedantic mode, as it
             // might have been in a header file referring to a module we never
             // needed so there are false positives

test_regress/t/t_mailbox_std.pl

@@ -17,7 +17,7 @@ else {
     top_filename("t/t_mailbox.v");
 
     compile(
-        verilator_flags2 => ["--exe --main --timing -Wall -DMAILBOX_T=std::mailbox"],
+        verilator_flags2 => ["--exe --main --timing -Wall --Wpedantic -DMAILBOX_T=std::mailbox"],
         make_main => 0,
         );