libssh: libhpp: avoid unnecessary call to ssh_channel_read

ssh_channel_read is a wrapper for ssh_channel_read_timeout with timeout
-1 (infinite) so we call that directly.

Signed-off-by: Petar Koretic <petar.koretic@sartura.hr>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit c51f42a566)

include/libssh/libsshpp.hpp

@@ -485,7 +485,7 @@ public:
     /* handle int overflow */
     if(count > 0x7fffffff)
       count = 0x7fffffff;
-    err=ssh_channel_read(channel,dest,count,is_stderr);
+    err=ssh_channel_read_timeout(channel,dest,count,is_stderr,-1);
     ssh_throw(err);
     return err;
   }