PROV: make some DER AID arrays non-static, to avoid clang complaints

The problem encountered is that some arrays were deemed unnecessary by
clang, for example:

    providers/common/der/der_rsa.c:424:28: error: variable 'der_aid_sha224Identifier' is not needed and will not be emitted [-Werror,-Wunneeded-internal-declaration]
    static const unsigned char der_aid_sha224Identifier[] = {
                               ^

However, these arrays are used in sizeof() expressions in other parts
of the code that's actually used, making that warning-turned-error a
practical problem.  We solve this by making the array non-static,
which guarantees that the arrays will be emitted, even though
unnecessarily.  Fortunately, they are very small.
Reviewed-by: NShane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11710)

providers/common/der/der_rsa.c.in

@@ -50,13 +50,20 @@
  * sha384Identifier  AlgorithmIdentifier  ::=  { id-sha384, NULL }
  * sha512Identifier  AlgorithmIdentifier  ::=  { id-sha512, NULL }
  */
+/*
+ * NOTE: Some of the arrays aren't used other than inside sizeof(), which
+ * clang complains about (-Wno-unneeded-internal-declaration).  To get
+ * around that, we make them non-static, and declare them an extra time to
+ * avoid compilers complaining about definitions without declarations.
+ */
 #if 0                            /* Currently unused */
 #define DER_AID_V_sha1Identifier                                        \
     DER_P_SEQUENCE|DER_F_CONSTRUCTED,                                   \
         DER_OID_SZ_id_sha1 + DER_SZ_NULL,                               \
         DER_OID_V_id_sha1,                                              \
         DER_V_NULL
-static const unsigned char der_aid_sha1Identifier[] = {
+extern const unsigned char der_aid_sha1Identifier[];
+const unsigned char der_aid_sha1Identifier[] = {
     DER_AID_V_sha1Identifier
 };
 #define DER_AID_SZ_sha1Identifier sizeof(der_aid_sha1Identifier)
@@ -67,7 +74,8 @@ static const unsigned char der_aid_sha1Identifier[] = {
         DER_OID_SZ_id_sha224 + DER_SZ_NULL,                             \
         DER_OID_V_id_sha224,                                            \
         DER_V_NULL
-static const unsigned char der_aid_sha224Identifier[] = {
+extern const unsigned char der_aid_sha224Identifier[];
+const unsigned char der_aid_sha224Identifier[] = {
     DER_AID_V_sha224Identifier
 };
 #define DER_AID_SZ_sha224Identifier sizeof(der_aid_sha224Identifier)
@@ -77,7 +85,8 @@ static const unsigned char der_aid_sha224Identifier[] = {
         DER_OID_SZ_id_sha256 + DER_SZ_NULL,                             \
         DER_OID_V_id_sha256,                                            \
         DER_V_NULL
-static const unsigned char der_aid_sha256Identifier[] = {
+extern const unsigned char der_aid_sha256Identifier[];
+const unsigned char der_aid_sha256Identifier[] = {
     DER_AID_V_sha256Identifier
 };
 #define DER_AID_SZ_sha256Identifier sizeof(der_aid_sha256Identifier)
@@ -87,7 +96,8 @@ static const unsigned char der_aid_sha256Identifier[] = {
         DER_OID_SZ_id_sha384 + DER_SZ_NULL,                             \
         DER_OID_V_id_sha384,                                            \
         DER_V_NULL
-static const unsigned char der_aid_sha384Identifier[] = {
+extern const unsigned char der_aid_sha384Identifier[];
+const unsigned char der_aid_sha384Identifier[] = {
     DER_AID_V_sha384Identifier
 };
 #define DER_AID_SZ_sha384Identifier sizeof(der_aid_sha384Identifier)
@@ -97,7 +107,8 @@ static const unsigned char der_aid_sha384Identifier[] = {
         DER_OID_SZ_id_sha512 + DER_SZ_NULL,                             \
         DER_OID_V_id_sha512,                                            \
         DER_V_NULL
-static const unsigned char der_aid_sha512Identifier[] = {
+extern const unsigned char der_aid_sha512Identifier[];
+const unsigned char der_aid_sha512Identifier[] = {
     DER_AID_V_sha512Identifier
 };
 #define DER_AID_SZ_sha512Identifier sizeof(der_aid_sha512Identifier)
@@ -107,7 +118,8 @@ static const unsigned char der_aid_sha512Identifier[] = {
         DER_OID_SZ_id_sha512_224 + DER_SZ_NULL,                         \
         DER_OID_V_id_sha512_224,                                        \
         DER_V_NULL
-static const unsigned char der_aid_sha512_224Identifier[] = {
+extern const unsigned char der_aid_sha512_224Identifier[];
+const unsigned char der_aid_sha512_224Identifier[] = {
     DER_AID_V_sha512_224Identifier
 };
 #define DER_AID_SZ_sha512_224Identifier sizeof(der_aid_sha512_224Identifier)
@@ -117,7 +129,8 @@ static const unsigned char der_aid_sha512_224Identifier[] = {
         DER_OID_SZ_id_sha512_256 + DER_SZ_NULL,                         \
         DER_OID_V_id_sha512_256,                                        \
         DER_V_NULL
-static const unsigned char der_aid_sha512_256Identifier[] = {
+extern const unsigned char der_aid_sha512_256Identifier[];
+const unsigned char der_aid_sha512_256Identifier[] = {
     DER_AID_V_sha512_256Identifier
 };
 #define DER_AID_SZ_sha512_256Identifier sizeof(der_aid_sha512_256Identifier)