set missing keylength for field 'EnvName'

Fixes #356: BLOB/TEXT column 'EnvName' keylengt is missing mysql

Signed-off-by: Marco van Wieringen <marco.van.wieringen@bareos.com>
Compile NDMP code with C-compiler and use CFLAGS.
Fix build when using GNUTLS instead of OpenSSL
Make estimate command somewhat more robust.

Fixes #349: Director crashes on estimate command of Copy Job
New version including all fixes until today.