Fix std::process::get_randstate to not affect random stability (#6550) (#6565)

include/verilated.cpp

@@ -294,6 +294,16 @@ void VL_PRINTF_MT(const char* formatp, ...) VL_MT_SAFE {
     }});
 }
 
+//===========================================================================
+// Process -- parts of std::process implementation
+
+std::string VlProcess::randstate() const VL_MT_UNSAFE {
+    return VlRNG::vl_thread_rng().get_randstate();
+}
+void VlProcess::randstate(const std::string& state) VL_MT_UNSAFE {
+    VlRNG::vl_thread_rng().set_randstate(state);
+}
+
 //===========================================================================
 // Random -- Mostly called at init time, so not inline.