lbutils: remove more unused macros

detected via clang -Weverything

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/lib/mkhtemp.c

@@ -4,10 +4,6 @@
  * Hardened mktemp (be nice to the demon).
  */
 
-#ifndef _XOPEN_SOURCE
-#define _XOPEN_SOURCE 700
-#endif
-
 /* for openat2 / fast path: */
 #ifdef __linux__
 #if !defined(USE_OPENAT) || \

util/libreboot-utils/lib/rand.c

@@ -4,9 +4,6 @@
  * Random number generation
  */
 
-#ifndef RAND_H
-#define RAND_H
-
 #if defined(USE_ARC4) && \
     ((USE_ARC4) > 0)
 #define _DEFAULT_SOURCE 1 /* for arc4random on *linux* */
@@ -201,4 +198,3 @@ err:
 	exitf("Randomisierungsfehler");
 	exit(EXIT_FAILURE);
 }
-#endif