[DRWTSN32] Add SMBIOS data to the system information (#1017)

[DMILIB][UDMIHELP] Allow functions to be linked with C++ code.

sdk/lib/dmilib/dmilib.h

@@ -6,7 +6,8 @@
  * PROGRAMMERS: Timo Kreuzer (timo.kreuzer@reactos.org)
  */
 
-#pragma once
+#ifndef DMILIB_H
+#define DMILIB_H
 
 enum _ID_STRINGS
 {
@@ -34,3 +35,5 @@ ParseSMBiosTables(
     _In_reads_bytes_(TableSize) PVOID SMBiosTables,
     _In_ ULONG TableSize,
     _Inout_updates_(ID_STRINGS_MAX) PCHAR * Strings);
+
+#endif /* DMILIB_H */

sdk/lib/udmihelp/udmihelp.h

@@ -5,7 +5,14 @@
  * COPYRIGHT:   Copyright 2018 Stanislav Motylkov
  */
 
-#pragma once
+#ifndef UDMIHELP_H
+#define UDMIHELP_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <../dmilib/dmilib.h>
 
 PVOID
 LoadSMBiosData(
@@ -25,3 +32,9 @@ GetSMBiosStringW(
 VOID
 FreeSMBiosData(
     _In_ PVOID Buffer);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* UDMIHELP_H */