areusch review: New workaround for multiple runs on micro targets

Instead of not calling FreeHandle() when a session terminates on the
host side, avoid calling TVMFreeMod() for system_lib_handle on the
target side.

src/runtime/crt/common/crt_runtime_api.c

@@ -183,7 +183,17 @@ int TVMModCreateFromCModule(const TVMModule* mod, TVMModuleHandle* out_handle) {
   return -1;
 }
 
+static const TVMModuleHandle kTVMModuleHandleUninitialized = (TVMModuleHandle)(~0UL);
+
+static TVMModuleHandle system_lib_handle;
+
 int TVMModFree(TVMModuleHandle mod) {
+  /* Never free system_lib_handler */
+  if (mod == system_lib_handle &&
+      system_lib_handle != kTVMModuleHandleUninitialized) {
+    return 0;
+  }
+
   tvm_module_index_t module_index;
   if (DecodeModuleHandle(mod, &module_index) != 0) {
     return -1;
@@ -193,10 +203,6 @@ int TVMModFree(TVMModuleHandle mod) {
   return 0;
 }
 
-static const TVMModuleHandle kTVMModuleHandleUninitialized = (TVMModuleHandle)(~0UL);
-
-static TVMModuleHandle system_lib_handle;
-
 int SystemLibraryCreate(TVMValue* args, int* type_codes, int num_args, TVMValue* ret_val,
                         int* ret_type_codes) {
   const TVMModule* system_lib;