OvmfPkg/SmbiosPlatformDxe: declare InstallAllStructures() in header file
    
    Add an extern declaration for the InstallAllStructures() function to the
    "SmbiosPlatformDxe.h" header file. (The leading comment block and the
    prototype are simply copied from "SmbiosPlatformDxe.c".)
    
    Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
    Cc: Jordan Justen <jordan.l.justen@intel.com>
    Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
    Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2122
    Signed-off-by: Laszlo Ersek <lersek@redhat.com>
    Message-Id: <20210526201446.12554-41-lersek@redhat.com>
    Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
    Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>