BLOCK_ADJUST_ERRNO: move rc to right level

We can't declare the variable within the block and use it in the final
do-while() expression to be properly portable C89.

src/session.h

@@ -56,8 +56,8 @@
        time_t entry_time = time (NULL); \
        do { \
           rc = x; \
-          /* the order of the check below is important to properly deal with the
+          /* the order of the check below is important to properly deal with \
-             case when the 'sess' is freed */ \
+             the case when the 'sess' is freed */ \
           if((rc != LIBSSH2_ERROR_EAGAIN) || !sess->api_block_mode) \
               break; \
           rc = _libssh2_wait_socket(sess, entry_time);  \
@@ -73,8 +73,8 @@
 #define BLOCK_ADJUST_ERRNO(ptr,sess,x) \
     do { \
        time_t entry_time = time (NULL); \
+       int rc; \
        do { \
-           int rc; \
            ptr = x; \
            if(!sess->api_block_mode || \
               (ptr != NULL) || \