Make the global DRBGs static

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
GH: #4268

crypto/rand/drbg_lib.c

diff --git a/crypto/rand/drbg_lib.c b/crypto/rand/drbg_lib.c
index 3690976..83ddc27 100644
--- a/crypto/rand/drbg_lib.c
+++ b/crypto/rand/drbg_lib.c
@@ -15,6 +15,9 @@
 #include "internal/thread_once.h"
 #include "internal/rand_int.h"
 
+static RAND_DRBG rand_drbg; /* The default global DRBG. */
+static RAND_DRBG priv_drbg; /* The global private-key DRBG. */
+
 /*
  * Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
  * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
@@ -473,9 +476,6 @@
     return &priv_drbg;
 }
 
-RAND_DRBG rand_drbg; /* The default global DRBG. */
-RAND_DRBG priv_drbg; /* The global private-key DRBG. */
-
 RAND_METHOD rand_meth = {
     drbg_seed,
     drbg_bytes,

crypto/rand/rand_lcl.h

diff --git a/crypto/rand/rand_lcl.h b/crypto/rand/rand_lcl.h
index f9de279..498b7e6 100644
--- a/crypto/rand/rand_lcl.h
+++ b/crypto/rand/rand_lcl.h
@@ -144,8 +144,6 @@
 /* The global RAND method, and the global buffer and DRBG instance. */
 extern RAND_METHOD rand_meth;
 extern RAND_BYTES_BUFFER rand_bytes;
-extern RAND_DRBG rand_drbg;
-extern RAND_DRBG priv_drbg;
 
 /* How often we've forked (only incremented in child). */
 extern int rand_fork_count;