Remove unnecessary assignment of |e| in |rsa_setup_blinding|.

After its initial assignment, |e| is immediately reassigned another
value and so the initial assignment from |BN_CTX_get| is useless. If
that were not the case, then the |BN_free(e)| at the end of the
function would be very bad.

Change-Id: Id63a172073501c8ac157db9188a22f55ee36b205
Reviewed-on: https://boringssl-review.googlesource.com/6951
Reviewed-by: David Benjamin <davidben@google.com>

crypto/rsa/blinding.c

diff --git a/crypto/rsa/blinding.c b/crypto/rsa/blinding.c
index d21633f..5addddc 100644
--- a/crypto/rsa/blinding.c
+++ b/crypto/rsa/blinding.c
@@ -415,13 +415,6 @@
     ctx = in_ctx;
   }
 
-  BN_CTX_start(ctx);
-  e = BN_CTX_get(ctx);
-  if (e == NULL) {
-    OPENSSL_PUT_ERROR(RSA, ERR_R_MALLOC_FAILURE);
-    goto err;
-  }
-
   if (rsa->e == NULL) {
     e = rsa_get_public_exp(rsa->d, rsa->p, rsa->q, ctx);
     if (e == NULL) {
@@ -450,7 +443,6 @@
   }
 
 err:
-  BN_CTX_end(ctx);
   if (in_ctx == NULL) {
     BN_CTX_free(ctx);
   }