Fix warnings found by clang in CI

Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from https://github.com/openssl/openssl/pull/24047)

demos/cipher/aesccm.c

@@ -64,8 +64,8 @@ static const unsigned char ccm_tag[] = {
  * algorithm implementations. If they are NULL then the default library
  * context and properties are used.
  */
-OSSL_LIB_CTX *libctx = NULL;
-const char *propq = NULL;
+static OSSL_LIB_CTX *libctx = NULL;
+static const char *propq = NULL;
 
 
 static int aes_ccm_encrypt(void)

demos/cipher/aesgcm.c

@@ -64,8 +64,8 @@ static const unsigned char gcm_tag[] = {
  * algorithm implementations. If they are NULL then the default library
  * context and properties are used.
  */
-OSSL_LIB_CTX *libctx = NULL;
-const char *propq = NULL;
+static OSSL_LIB_CTX *libctx = NULL;
+static const char *propq = NULL;
 
 static int aes_gcm_encrypt(void)
 {

demos/cipher/aeskeywrap.c

@@ -50,8 +50,8 @@ static const unsigned char wrap_ct[] = {
  * algorithm implementations. If they are NULL then the default library
  * context and properties are used.
  */
-OSSL_LIB_CTX *libctx = NULL;
-const char *propq = NULL;
+static OSSL_LIB_CTX *libctx = NULL;
+static const char *propq = NULL;
 
 static int aes_wrap_encrypt(void)
 {

demos/cipher/ariacbc.c

@@ -49,8 +49,8 @@ static const unsigned char cbc_ct[] = {
  * algorithm implementations. If they are NULL then the default library
  * context and properties are used.
  */
-OSSL_LIB_CTX *libctx = NULL;
-const char *propq = NULL;
+static OSSL_LIB_CTX *libctx = NULL;
+static const char *propq = NULL;
 
 static int aria_cbc_encrypt(void)
 {

demos/digest/EVP_MD_demo.c

@@ -24,7 +24,7 @@
  * more than once.
  */
 
-const char *hamlet_1 =
+static const char *hamlet_1 =
     "To be, or not to be, that is the question,\n"
     "Whether tis nobler in the minde to suffer\n"
     "The ſlings and arrowes of outragious fortune,\n"
@@ -43,7 +43,7 @@ const char *hamlet_1 =
     "The oppressor's wrong, the proud man's Contumely,\n"
     "The pangs of dispised love, the Law's delay,\n"
 ;
-const char *hamlet_2 =
+static const char *hamlet_2 =
     "The insolence of Office, and the spurns\n"
     "That patient merit of the'unworthy takes,\n"
     "When he himself might his Quietas make\n"
@@ -65,7 +65,7 @@ const char *hamlet_2 =
 ;
 
 /* The known value of the SHA3-512 digest of the above soliloqy */
-const unsigned char known_answer[] = {
+static const unsigned char known_answer[] = {
     0xbb, 0x69, 0xf8, 0x09, 0x9c, 0x2e, 0x00, 0x3d,
     0xa4, 0x29, 0x5f, 0x59, 0x4b, 0x89, 0xe4, 0xd9,
     0xdb, 0xa2, 0xe5, 0xaf, 0xa5, 0x87, 0x73, 0x9d,

demos/digest/EVP_MD_xof.c

@@ -27,7 +27,7 @@
  */
 
 /* Our input to the XOF hash function. */
-const char message[] = "This is a test message.";
+static const char message[] = "This is a test message.";
 
 /* Expected output when an output length of 20 bytes is used. */
 static const unsigned char known_answer[] = {

demos/guide/quic-client-non-block.c

@@ -231,7 +231,7 @@ int main(int argc, char *argv[])
     unsigned char alpn[] = { 8, 'h', 't', 't', 'p', '/', '1', '.', '0' };
     const char *request_start = "GET / HTTP/1.0\r\nConnection: close\r\nHost: ";
     const char *request_end = "\r\n\r\n";
-    size_t written, readbytes;
+    size_t written, readbytes = 0;
     char buf[160];
     BIO_ADDR *peer_addr = NULL;
     int eof = 0;

demos/guide/tls-client-non-block.c

@@ -183,7 +183,7 @@ int main(int argc, char *argv[])
     int ret;
     const char *request_start = "GET / HTTP/1.0\r\nConnection: close\r\nHost: ";
     const char *request_end = "\r\n\r\n";
-    size_t written, readbytes;
+    size_t written, readbytes = 0;
     char buf[160];
     int eof = 0;
     char *hostname, *port;

demos/pkey/EVP_PKEY_DSA_paramvalidate.c

@@ -47,8 +47,8 @@ static const char hexseed[] =
     "cba30ccd905aa7675a0b81769704bf3c"
     "ccf2ca1892b2eaf6b9e2b38d9bf6affc"
     "42ada55986d8a1772b442770954d0b65";
-const int gindex = 42;
-const int pcounter = 363;
+static const int gindex = 42;
+static const int pcounter = 363;
 static const char digest[] = "SHA384";
 
 /*