compile/download scripts need to exit with positive error code on wrong parameters

Problem: If one of the donwload task fails the script do not stop and
the other task continue to donwload sources.

Solution: If one of the task fails, print an informative error message
and send a signal to the parent process that kills all the spawned tasks
and exits with error code.

When rocksdb is build with jemalloc linking with adafs was failing

The download script do not work if the specified output path
contains more then 1 non-existing folder.
This is due to the -f flag used in the readlink command.
We now use the less strict -m one.

Source folder was removed if existed before but never recreated

Since the download of sources are performed in parallel, we cannot use
anymore a single log file.

The output of the download commands has been reduced to errrors only and
it will be outputted directly on stderr. Thus the log file stuff have been
completely removed.

Moreover the clonedeps function now takes the REPO as second parameter
and additional (non mandatory) git flags as fourth parameter.

Additional fixes have been introduced to run commands in script mode
(-q, -f, ...)

For dependencies in which a specific tags is specified we can download
the code snapshot instead of cloning the whole repo.

Perform all the download and git clone action in parallel using several
processes.

Due to the new parallel use of the clonedeps and wgetdeps functions,
some adjustment to printed message has been made. Now the function write
on stdout only once when they complete.

The specific version is necessary for local I/O to work.

See https://xgitlab.cels.anl.gov/sds/margo/issues/40 for reference of the issue.

5.10.2 -> 5.10.3

5.10.2 couldn't be compiled with gcc 7 due to a rocksDB bug [1]

[1]: https://github.com/facebook/rocksdb/issues/3486

The download script can be used to update dependencies source code by
pull the new version and performing a checkout to that version.
Without forcing (-f) the checkout files that have been modified or
patched won't be updated correctly.