test/fsprg: move includes to appease clang-tidy

Previously in CI:
../src/test/fsprg.c:18:1: error: included header gcrypt-util.h is not used directly [misc-include-cleaner,-warnings-as-errors]
   18 | #include "gcrypt-util.h"
      | ^~~~~~~~~~~~~~~~~~~~~~~~
   19 | #include "memory-util.h"
../src/test/fsprg.c:19:1: error: included header memory-util.h is not used directly [misc-include-cleaner,-warnings-as-errors]
   19 | #include "memory-util.h"
      | ^~~~~~~~~~~~~~~~~~~~~~~~
   20 |
2 warnings treated as errors

(cherry picked from commit 1f286f971e)

src/test/fsprg.c

@@ -15,8 +15,6 @@
 #include <string.h>
 
 #include "fsprg.h"
-#include "gcrypt-util.h"
-#include "memory-util.h"
 
 #define ISVALID_SECPAR(secpar) (((secpar) % 16 == 0) && ((secpar) >= 16) && ((secpar) <= 16384))
 #define VALIDATE_SECPAR(secpar) assert(ISVALID_SECPAR(secpar));
@@ -28,6 +26,9 @@
 
 #if HAVE_GCRYPT
 
+#include "gcrypt-util.h"
+#include "memory-util.h"
+
 #pragma GCC diagnostic ignored "-Wpointer-arith"
 /* TODO: remove void* arithmetic and this work-around */