Add: support for emscripten (play-OpenTTD-in-the-browser)

Emscripten compiles to WASM, which can be loaded via
HTML / JavaScript. This allows you to play OpenTTD inside a
browser.

Co-authored-by: milek7 <me@milek7.pl>

src/ini.cpp

@@ -13,6 +13,9 @@
 #include "string_func.h"
 #include "fileio_func.h"
 #include <fstream>
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
 
 #if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 199309L) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500)
 # include <unistd.h>
@@ -115,6 +118,10 @@ bool IniFile::SaveToDisk(const char *filename)
 	}
 #endif
 
+#ifdef __EMSCRIPTEN__
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+#endif
+
 	return true;
 }