Revert "[Macros] Terminate macro plugin"

This reverts commit 4a62ef8.

Author: hamishknight

lib/AST/PluginRegistry.cpp

@@ -213,7 +213,6 @@ LoadedExecutablePlugin::PluginProcess::~PluginProcess() {
 #else
   close(input);
   close(output);
-  kill(process.Pid, SIGTERM);
 #endif
 
   // Set `SecondsToWait` non-zero so it waits for the timeout and kill it after