Replace Boost.Asio with standalone Asio library

We had to add an even hackier hack now to get Boost.Process to
interoperate with Asio's IO contexts. This will be replaced later when
we replace Boost.Process.

src/common/mutual-recursion.h

@@ -21,10 +21,10 @@
 #include <type_traits>
 
 #ifdef __WINE__
-#include "../wine-host/boost-fix.h"
+#include "../wine-host/asio-fix.h"
 #endif
-#include <boost/asio/dispatch.hpp>
-#include <boost/asio/io_context.hpp>
+#include <asio/dispatch.hpp>
+#include <asio/io_context.hpp>
 
 /**
  * A helper to allow mutually recursive calling sequences with remote function
@@ -83,8 +83,8 @@ class MutualRecursionHelper {
         // as we need to support multiple levels of mutual recursion. This can
         // for instance happen during `IPlugView::attached() ->
         // IPlugFrame::resizeView() -> IPlugView::onSize()`.
-        std::shared_ptr<boost::asio::io_context> current_io_context =
-            std::make_shared<boost::asio::io_context>();
+        std::shared_ptr<asio::io_context> current_io_context =
+            std::make_shared<asio::io_context>();
         {
             std::unique_lock lock(mutual_recursion_contexts_mutex_);
             mutual_recursion_contexts_.push_back(current_io_context);
@@ -93,7 +93,7 @@ class MutualRecursionHelper {
         // Instead of directly stopping the IO context, we'll reset this work
         // guard instead. This prevents us from accidentally cancelling any
         // outstanding tasks.
-        auto work_guard = boost::asio::make_work_guard(*current_io_context);
+        auto work_guard = asio::make_work_guard(*current_io_context);
 
         // We will call the function from another thread so we can handle calls
         // to `handle()`/`maybe_handle()` from this thread
@@ -168,7 +168,7 @@ class MutualRecursionHelper {
         // pretend that we're not doing any async things here
         std::packaged_task<Result()> do_call(std::forward<F>(fn));
         std::future<Result> do_call_response = do_call.get_future();
-        boost::asio::dispatch(*mutual_recursion_contexts_.back(),
+        asio::dispatch(*mutual_recursion_contexts_.back(),
                               std::move(do_call));
         mutual_recursion_lock.unlock();
 
@@ -186,7 +186,7 @@ class MutualRecursionHelper {
      * active one. If the stack is empty, then there's currently no mutual
      * recursion going on.
      */
-    std::vector<std::shared_ptr<boost::asio::io_context>>
+    std::vector<std::shared_ptr<asio::io_context>>
         mutual_recursion_contexts_;
     std::mutex mutual_recursion_contexts_mutex_;
 };