Switch ruptura_main from stdcall to cdecl.

We don't use CreateRemoteThread to invoke it directly, so using cdecl simplifies
finding the symbol for 32-bit (no stdcall name mangling).

Part of #5.

Author: alexrp

src/injection/AssemblyInjector.cs

@@ -254,6 +254,7 @@ async Task InjectModuleAsync(string modulePath, nuint parameterArea, MemoryMappe
 
                     asm.push(__dword_ptr[esp + 4]);
                     asm.call(eax);
+                    asm.add(esp, 4);
                     asm.jmp(done);
 
                     asm.Label(ref failure);

src/module/main.h

@@ -11,4 +11,4 @@ typedef struct
     uint32_t main_thread_id;
 } ruptura_parameters;
 
-__declspec(dllexport) uint32_t __stdcall ruptura_main(ruptura_parameters *nonnull parameters);
+__declspec(dllexport) uint32_t ruptura_main(ruptura_parameters *nonnull parameters);