Fix top-level unpacked structure resets (#5221).

src/V3AstNodeDType.h

@@ -219,6 +219,7 @@ public:
     bool isCompound() const override { return !packed(); }
     // For basicp() we reuse the size to indicate a "fake" basic type of same size
     AstBasicDType* basicp() const override {
+        if (!m_packed) return nullptr;
         return (isFourstate()
                     ? VN_AS(findLogicRangeDType(VNumRange{width() - 1, 0}, width(), numeric()),
                             BasicDType)

src/V3EmitCBase.cpp

@@ -211,11 +211,11 @@ void EmitCBaseVisitorConst::emitVarDecl(const AstVar* nodep, bool asRef) {
         if (nodep->isWide()) puts("," + cvtToStr(nodep->widthWords()));
         puts(");\n");
     } else {
-        // strings and other fundamental c types
+        // Strings and other fundamental C types
         if (nodep->isFuncLocal() && nodep->isString()) {
             const string name = nodep->name();
             const string suffix = V3Task::dpiTemporaryVarSuffix();
-            // string temporary variable for DPI-C needs to be static because c_str() will be
+            // String temporary variable for DPI-C needs to be static because c_str() will be
             // passed to C code and the lifetime of the variable must be long enough. See also
             // Issue 2622.
             const bool beStatic = name.size() >= suffix.size()