Cleanup : directly include of `internal/nelem.h` when required.

And so clean a few useless includes

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19721)

apps/s_client.c

@@ -15,6 +15,7 @@
 #include <string.h>
 #include <errno.h>
 #include <openssl/e_os2.h>
+#include "internal/nelem.h"
 
 #ifndef OPENSSL_NO_SOCK
 

crypto/ec/ec_backend.c

@@ -25,6 +25,7 @@
 #include "crypto/ec.h"
 #include "ec_local.h"
 #include "internal/e_os.h"
+#include "internal/nelem.h"
 #include "internal/param_build_set.h"
 
 /* Mapping between a flag and a name */

engines/e_devcrypto.c

@@ -25,6 +25,7 @@
 #include <openssl/engine.h>
 #include <openssl/objects.h>
 #include "crypto/cryptodev.h"
+#include "internal/nelem.h"
 
 /* #define ENGINE_DEVCRYPTO_DEBUG */
 

include/internal/e_os.h

@@ -15,7 +15,6 @@
 
 # include <openssl/e_os2.h>
 # include <openssl/crypto.h>
-# include "internal/nelem.h"
 # include "internal/numbers.h"   /* Ensure the definition of SIZE_MAX */
 
 /*

providers/baseprov.c

@@ -19,7 +19,6 @@
 #include "prov/providercommon.h"
 #include "prov/implementations.h"
 #include "prov/provider_util.h"
-#include "internal/nelem.h"
 
 /*
  * Forward declarations to ensure that interface functions are correctly

providers/common/provider_util.c

@@ -19,7 +19,6 @@
 # include "crypto/evp.h"
 #endif
 #include "prov/provider_util.h"
-#include "internal/nelem.h"
 
 void ossl_prov_cipher_reset(PROV_CIPHER *pc)
 {

providers/fips/fipsprov.c

@@ -21,6 +21,7 @@
 #include "prov/providercommon.h"
 #include "prov/provider_util.h"
 #include "prov/seeding.h"
+#include "internal/nelem.h"
 #include "self_test.h"
 #include "crypto/context.h"
 #include "internal/core.h"

providers/implementations/encode_decode/decode_der2key.c

@@ -35,6 +35,7 @@
 #include "prov/bio.h"
 #include "prov/implementations.h"
 #include "endecoder_local.h"
+#include "internal/nelem.h"
 
 struct der2key_ctx_st;           /* Forward declaration */
 typedef int check_key_fn(void *, struct der2key_ctx_st *ctx);

providers/implementations/kdfs/x942kdf.c

@@ -17,6 +17,7 @@
 #include <openssl/proverr.h>
 #include "internal/packet.h"
 #include "internal/der.h"
+#include "internal/nelem.h"
 #include "prov/provider_ctx.h"
 #include "prov/providercommon.h"
 #include "prov/implementations.h"

providers/implementations/kem/rsa_kem.c

@@ -23,6 +23,7 @@
 #include <openssl/err.h>
 #include "crypto/rsa.h"
 #include <openssl/proverr.h>
+#include "internal/nelem.h"
 #include "prov/provider_ctx.h"
 #include "prov/implementations.h"
 #include "prov/securitycheck.h"

providers/implementations/rands/seeding/rand_unix.c

@@ -18,6 +18,7 @@
 #include "crypto/rand_pool.h"
 #include "crypto/rand.h"
 #include "internal/dso.h"
+#include "internal/nelem.h"
 #include "prov/seeding.h"
 
 #ifdef __linux

providers/implementations/rands/seeding/rand_vms.c

@@ -12,6 +12,7 @@
 #define __NEW_STARLET 1         /* New starlet definitions since VMS 7.0 */
 #include <unistd.h>
 #include "internal/cryptlib.h"
+#include "internal/nelem.h"
 #include <openssl/rand.h>
 #include "crypto/rand.h"
 #include "crypto/rand_pool.h"

ssl/ssl_lib.c

@@ -23,6 +23,7 @@
 #include <openssl/trace.h>
 #include <openssl/core_names.h>
 #include "internal/cryptlib.h"
+#include "internal/nelem.h"
 #include "internal/refcount.h"
 #include "internal/ktls.h"
 

ssl/t1_trce.c

@@ -12,6 +12,7 @@
 #ifndef OPENSSL_NO_SSL_TRACE
 
 /* Packet trace support for OpenSSL */
+#include "internal/nelem.h"
 
 typedef struct {
     int num;

test/mdc2test.c

@@ -18,7 +18,6 @@
 #include <openssl/params.h>
 #include <openssl/types.h>
 #include <openssl/core_names.h>
-#include "internal/nelem.h"
 #include "testutil.h"
 
 #if defined(OPENSSL_NO_DES) && !defined(OPENSSL_NO_MDC2)

test/pkcs12_format_test.c

@@ -11,8 +11,6 @@
 #include <string.h>
 #include <stdlib.h>
 
-#include "internal/nelem.h"
-
 #include <openssl/pkcs12.h>
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>

test/testutil/format_output.c

@@ -13,7 +13,6 @@
 
 #include <string.h>
 #include <ctype.h>
-#include "internal/nelem.h"
 
 /* The size of memory buffers to display on failure */
 #define MEM_BUFFER_SIZE     (2000)

test/testutil/tests.c

@@ -14,7 +14,6 @@
 #include <errno.h>
 #include <string.h>
 #include <ctype.h>
-#include "internal/nelem.h"
 #include <openssl/asn1.h>
 
 /*

test/x509aux.c

@@ -16,7 +16,6 @@
 #include <openssl/pem.h>
 #include <openssl/conf.h>
 #include <openssl/err.h>
-#include "internal/nelem.h"
 #include "testutil.h"
 
 static int test_certs(int num)