Move PluginArchitecture to common

Along with the accompanying function to parse a PE32 file. We're going
to have to define some common tags for different plugin types.

src/common/plugins.h

@@ -0,0 +1,44 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#ifdef __WINE__
+#include "../wine-host/boost-fix.h"
+#endif
+#include <boost/filesystem.hpp>
+
+// Utilities and tags for plugin types and architectures
+
+/**
+ * A tag to differentiate between 32 and 64-bit plugins, used to determine which
+ * host application to use.
+ */
+enum class PluginArchitecture { vst_32, vst_64 };
+
+/**
+ * Determine the architecture of a VST plugin (or rather, a .dll file) based on
+ * it's header values.
+ *
+ * See https://docs.microsoft.com/en-us/windows/win32/debug/pe-format for more
+ * information on the PE32 format.
+ *
+ * @param plugin_path The path to the .dll file we're going to check.
+ *
+ * @return The detected architecture.
+ * @throw std::runtime_error If the file is not a .dll file.
+ */
+PluginArchitecture find_vst_architecture(boost::filesystem::path);