Kernel+LibC+Userland: Support mounting other kinds of filesystems

Author: https://github.com/bugaevc
Commit: 425c356288
Pull-request: https://github.com/SerenityOS/serenity/pull/456
Reviewed-by: https://github.com/awesomekling ✅

Kernel/Syscall.cpp

@@ -293,7 +293,7 @@ static u32 handle(RegisterDump& regs, u32 function, u32 arg1, u32 arg2, u32 arg3
         break;
     }
     case Syscall::SC_mount:
-        return current->process().sys$mount((const char*)arg1, (const char*)arg2);
+        return current->process().sys$mount((const char*)arg1, (const char*)arg2, (const char*)arg3);
     case Syscall::SC_reboot: {
         return current->process().sys$reboot();
     }