api: make nci.lib work on x86

This is an appalling hack. We need the lib tool to generate a coff lib
with the "undecorate" parameter. And apparently the only way to do this
with the MSVC tools is by making a stub object, and then rewriting the
symbols using the def file. See Q131313 for Microsoft-sanctioned
details.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

api/api.vcxproj

@@ -121,7 +121,8 @@
       <PreprocessorDefinitions Condition="'$(Platform)'=='ARM64'">_M_ARM64=1;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ResourceCompile>
     <PreLinkEvent>
-      <Command>lib.exe /def:nci.def /out:"$(IntDir)nci.lib" /machine:$(PlatformTarget) /nologo</Command>
+      <Command>cl.exe /nologo /DGENERATE_LIB /Ob0 /c /Fo"$(IntDir)nci.obj" /Tc nci.h
+lib.exe /def:nci.def /out:"$(IntDir)nci.lib" /machine:$(PlatformTarget) /nologo "$(IntDir)nci.obj"</Command>
     </PreLinkEvent>
     <Link>
       <DelayLoadDLLs>bcrypt.dll;iphlpapi.dll;nci.dll;newdev.dll;version.dll</DelayLoadDLLs>

api/exports.def

@@ -1,3 +1,4 @@
+LIBRARY wintun.dll
 EXPORTS
 	WintunAllocateSendPacket
 	WintunCreateAdapter

api/nci.def

@@ -1,3 +1,4 @@
+LIBRARY nci.dll
 EXPORTS
 	NciGetConnectionName
 	NciSetConnectionName

api/nci.h

@@ -7,10 +7,21 @@
 
 #include <Windows.h>
 
-extern DWORD WINAPI NciSetConnectionName(_In_ const GUID *Guid, _In_z_ const WCHAR *NewName);
+#ifdef GENERATE_LIB
+#    define DECLSPEC __declspec(dllexport)
+#    define STUB { return 0; }
+#else
+#    define DECLSPEC __declspec(dllimport)
+#    define STUB ;
+#endif
 
-extern DWORD WINAPI NciGetConnectionName(
+
+EXTERN_C DECLSPEC DWORD WINAPI
+NciSetConnectionName(_In_ const GUID *Guid, _In_z_ const WCHAR *NewName) STUB
+
+EXTERN_C DECLSPEC DWORD WINAPI
+NciGetConnectionName(
     _In_ const GUID *Guid,
     _Out_z_bytecap_(InDestNameBytes) WCHAR *Name,
     _In_ DWORD InDestNameBytes,
-    _Out_opt_ DWORD *OutDestNameBytes);
+    _Out_opt_ DWORD *OutDestNameBytes) STUB