[win32] remove __iob_func

* we prefer vcpkg libraries build using the same compiler
* VC++ 2017 is ABI compatible with 2017: https://docs.microsoft.com/en-gb/cpp/porting/binary-compat-2015-2017?view=vs-2019

src/celestia/qt/qtmain.cpp

@@ -36,7 +36,6 @@
 
 using namespace std;
 
-extern "C" { FILE __iob_func[3] = { *stdin,*stdout,*stderr }; }
 //static const char *description = "Celestia";
 
 // Command line options

src/celestia/win32/CMakeLists.txt

@@ -4,7 +4,6 @@ if(NOT WIN32 OR NOT ENABLE_WIN)
 endif()
 
 set(WIN32_SOURCES
-  iob_func_shim.cpp
   ODMenu.cpp
   wglext.cpp
   winbookmarks.cpp

src/celestia/win32/iob_func_shim.cpp

@@ -1,12 +0,0 @@
-#include <stdio.h>
-
-/*
-Since we're including static libraries that may have been built using
-an older version of Visual Studio, they may have been linked with a
-different definition of __iob_func() than the current one. This shim
-provides the old-style version of this function for these static
-libraries to consume.
-*/
-
-FILE ___iob[] = { *stdin, *stdout, *stderr };
-extern "C" FILE * __cdecl __iob_func(void) { return ___iob; }