Fix building with Clang 20

date: 3.0.4
tomlplusplus: Latest master as of writing since there's no stable release with the build fixes.

src/xenia/base/console_app_main_posix.cc

@@ -14,7 +14,7 @@
 #include "xenia/base/cvar.h"
 #include "xenia/base/logging.h"
 
-extern "C" int main(int argc, char** argv) {
+int main(int argc, char** argv) {
   xe::ConsoleAppEntryInfo entry_info = xe::GetConsoleAppEntryInfo();
 
   if (!entry_info.transparent_options) {

src/xenia/ui/windowed_app_main_posix.cc

@@ -17,7 +17,7 @@
 #include "xenia/ui/windowed_app.h"
 #include "xenia/ui/windowed_app_context_gtk.h"
 
-extern "C" int main(int argc_pre_gtk, char** argv_pre_gtk) {
+int main(int argc_pre_gtk, char** argv_pre_gtk) {
   // Before touching anything GTK+, make sure that when running on Wayland,
   // we'll still get an X11 (Xwayland) window
   setenv("GDK_BACKEND", "x11", 1);