xemu: fix Windows build

[oltolm]

I build xemu using MSYS2's UCRT64 environment and I use cmd instead of bash. This patch makes it build. There is also another patch for QEMU necessary, but I already submitted it upstream and it has been merged.

[oltolm]

I don't know why the python script was failing. I reverted the changes to the script and now it only has fixes for building with GCC.

[mborgerson]

Why is it necessary to move this include out of the extern "C" block? What is the error you're encountering when building? xemu is currently compiling with GCC 15 for Windows x86_64 on CI

[oltolm]

This is the error

[7/31] Compiling C++ object libsystem.a.p/C__src_xemu_ui_xui_animation.cc.obj
FAILED: [code=1] libsystem.a.p/C__src_xemu_ui_xui_animation.cc.obj
"c++" "-m64" "-Ilibsystem.a.p" "-I." "-IC:\src\xemu" "-Ithirdparty\nvapi" "-IC:\src\xemu\thirdparty\nvapi" "-Isubprojects\imgui" "-IC:\src\xemu\subprojects\imgui" "-IC:\src\xemu\subprojects\imgui\backends" "-Isubprojects\implot" "-IC:\src\xemu\subprojects\implot" "-IC:\src\xemu\ui\thirdparty\stb_image" "-IC:\src\xemu\ui\thirdparty\fa" "-IC:\src\xemu\ui\thirdparty\fpng" "-IC:\src\xemu\ui\thirdparty\fatx" "-Isubprojects\tomlplusplus\include" "-IC:\src\xemu\subprojects\tomlplusplus\include" "-Isubprojects\genconfig" "-IC:\src\xemu\subprojects\genconfig" "-IC:\src\xemu\winpcap-loader\include" "-Iqapi" "-Itrace" "-Iui" "-Iui\shader" "-Idata" "-IC:/msys64/ucrt64/include/libusb-1.0" "-IC:/msys64/ucrt64/include/slirp" "-IC:/msys64/ucrt64/include/glib-2.0" "-IC:/msys64/ucrt64/lib/glib-2.0/include" "-fdiagnostics-color=auto" "-D_GLIBCXX_ASSERTIONS=1" "-Wall" "-Winvalid-pch" "-std=c++17" "-O2" "-g" "-D__STDC_LIMIT_MACROS" "-D__STDC_CONSTANT_MACROS" "-D__STDC_FORMAT_MACROS" "-Wempty-body" "-Wendif-labels" "-Wexpansion-to-defined" "-Wformat-security" "-Wformat-y2k" "-Wignored-qualifiers" "-Wimplicit-fallthrough=2" "-Winit-self" "-Wmissing-format-attribute" "-Wredundant-decls" "-Wshadow=local" "-Wtype-limits" "-Wwrite-strings" "-Wno-missing-include-dirs" "-Wno-psabi" "-Wno-shift-negative-value" "-iquote" "." "-iquote" "C:\src\xemu" "-iquote" "C:/src/xemu/include" "-iquote" "C:/src/xemu/host/include/x86_64" "-iquote" "C:/src/xemu/host/include/generic" "-iquote" "C:/src/xemu/tcg/i386" "-mcx16" "-msse2" "-D_GNU_SOURCE" "-D_FILE_OFFSET_BITS=64" "-D_LARGEFILE_SOURCE" "-fno-strict-aliasing" "-fno-common" "-fwrapv" "-fno-pie" "-no-pie" "-ftrivial-auto-var-init=zero" "-fzero-call-used-regs=used-gpr" "-Wno-error" "-DTOML_HEADER_ONLY=0" "-Wno-undef" "-DIMGUI_API=" -MD -MQ libsystem.a.p/C__src_xemu_ui_xui_animation.cc.obj -MF "libsystem.a.p\C__src_xemu_ui_xui_animation.cc.obj.d" -o libsystem.a.p/C__src_xemu_ui_xui_animation.cc.obj "-c" C:/src/xemu/ui/xui/animation.cc
In file included from C:/msys64/ucrt64/include/glib-2.0/glib.h:107,
                 from C:/src/xemu/include/glib-compat.h:32,
                 from C:/src/xemu/include/qemu/osdep.h:175,
                 from C:/src/xemu/ui/xui/common.hh:36,
                 from C:/src/xemu/ui/xui/animation.cc:20:
C:/msys64/ucrt64/include/glib-2.0/glib/gwin32.h:178:1: error: template with C linkage
  178 | template <typename com_interface>
      | ^~~~~~~~
C:/src/xemu/ui/xui/common.hh:34:1: note: 'extern "C"' linkage started here
   34 | extern "C" {
      | ^~~~~~~~~~