VDE networking support

Adds VDE (https://github.com/virtualsquare/vde-2) support to 86Box.
- Adds new networking type
- Modifies networking configuration dialog
- Adds CMake Presets to build and debug under MacOS

src/network/CMakeLists.txt

@@ -12,8 +12,8 @@
 #
 #          Copyright 2020-2021 David Hrdlička.
 #
-
-add_library(net OBJECT network.c net_pcap.c net_slirp.c net_dp8390.c net_3c501.c
+set(net_sources)
+list(APPEND net_sources network.c net_pcap.c net_slirp.c net_dp8390.c net_3c501.c
     net_3c503.c net_ne2000.c net_pcnet.c net_wd8003.c net_plip.c net_event.c)
 
 option(SLIRP_EXTERNAL "Link against the system-provided libslirp library" OFF)
@@ -39,3 +39,13 @@ endif()
 if(WIN32)
     target_link_libraries(86Box ws2_32)
 endif()
+
+if (UNIX)
+    find_path(HAS_VDE "libvdeplug.h" PATHS ${VDE_INCLUDE_DIR} "/usr/include /usr/local/include" "/opt/homebrew/include" )
+    if(HAS_VDE)
+        add_compile_definitions(HAS_VDE)
+        list(APPEND net_sources net_vde.c)
+    endif()
+endif()
+
+add_library(net OBJECT ${net_sources})