Add do-nothing compatibility function |ERR_load_ERR_strings|.

Change-Id: I9ad06017b7b726e4529367ad244ae8945853ce62
Reviewed-on: https://boringssl-review.googlesource.com/4603
Reviewed-by: Adam Langley <agl@google.com>

crypto/err/err.c

diff --git a/crypto/err/err.c b/crypto/err/err.c
index 53ec538..b879a22 100644
--- a/crypto/err/err.c
+++ b/crypto/err/err.c
@@ -787,3 +787,5 @@
 void ERR_free_strings(void) {}
 
 void ERR_load_BIO_strings(void) {}
+
+void ERR_load_ERR_strings(void) {}

include/openssl/err.h

diff --git a/include/openssl/err.h b/include/openssl/err.h
index ff8bff5..e591534 100644
--- a/include/openssl/err.h
+++ b/include/openssl/err.h
@@ -142,6 +142,14 @@
 
 /* Startup and shutdown. */
 
+/* ERR_load_BIO_strings does nothing.
+ *
+ * TODO(fork): remove. libjingle calls this. */
+OPENSSL_EXPORT void ERR_load_BIO_strings(void);
+
+/* ERR_load_ERR_strings does nothing. */
+OPENSSL_EXPORT void ERR_load_ERR_strings(void);
+
 /* ERR_load_crypto_strings does nothing. */
 OPENSSL_EXPORT void ERR_load_crypto_strings(void);
 
@@ -487,11 +495,6 @@
  * ${lib}_F_${reason}. */
 #define OPENSSL_DECLARE_ERROR_FUNCTION(lib, function_name)
 
-/* ERR_load_BIO_strings does nothing.
- *
- * TODO(fork): remove. libjingle calls this. */
-OPENSSL_EXPORT void ERR_load_BIO_strings(void);
-
 
 /* Android compatibility section.
  *