Fix examples not flushing vcd (#2787).

Changes

@@ -9,6 +9,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix $fread extra semicolon inside statements. [Leendert van Doorn]
 
+****  Fix examples not flushing vcd (#2787).  [Richard E George]
+
 
 * Verilator 4.108 2021-01-10
 

examples/make_hello_c/sim_main.cpp

@@ -38,5 +38,5 @@ int main(int argc, char** argv, char** env) {
     delete top;
 
     // Return good completion status
-    exit(0);
+    return 0;
 }

examples/make_protect_lib/sim_main.cpp

@@ -71,5 +71,6 @@ int main(int argc, char** argv, char** env) {
     top = nullptr;
 
     // Return good completion status
-    exit(0);
+    // Don't use exit() or destructor won't get called
+    return 0;
 }

examples/make_tracing_c/sim_main.cpp

@@ -102,5 +102,6 @@ int main(int argc, char** argv, char** env) {
 #endif
 
     // Return good completion status
-    exit(0);
+    // Don't use exit() or destructor won't get called
+    return 0;
 }