Free buffer on error in a2i_ASN1_INTEGER()

The function a2i_ASN1_INTEGER() allocates a buffer |s| but then fails
to free it on error paths.

Reviewed-by: Richard Levitte <levitte@openssl.org>

crypto/asn1/f_int.c

diff --git a/crypto/asn1/f_int.c b/crypto/asn1/f_int.c
index 15aece9..0f16ac0 100644
--- a/crypto/asn1/f_int.c
+++ b/crypto/asn1/f_int.c
@@ -148,6 +148,7 @@
     return 1;
  err:
     ASN1err(ASN1_F_A2I_ASN1_INTEGER, ASN1_R_SHORT_LINE);
+    OPENSSL_free(s);
     return 0;
 }