diracosrc: add DAVIX_USE_LIBCURL=1

[chaen]

BEGINRELEASENOTES
NEW: add DAVIX_USE_LIBCURL=1 in diracosrc
ENDRELEASENOTES

@chrisburr I wanted to do the same for DIRACOS2, but there is no diracosrc equivalent. How should we do ? (without this, we can segfault)

[chrisburr]

There is a diracosrc though that might not be the right place for it: https://github.com/DIRACGrid/DIRACOS2/blob/main/create_diracosrc.sh

Two questions:

• If davix segfaults without this why does it use an environment variable instead of being the default in the source code?
• Does everyone who uses davix ideally need this? If so, it could be set automatically by the conda-forge davix package when activating an environment

[chaen]

They are replacing neon by libcurl so this will soon not be needed anymore. And the segfault happens in our integration tests after a lot of operations (put, rm, mkdir, rmdir, etc, unlikely to happen in real life scenario), but is apparently tricky to reproduce, although I can systematically.

[chrisburr]

In that case can you add it to create_diracosrc.sh as it's less hassle than modifying the conda-package correctly (in particular accounting for all possible shells is tedious).

[chaen]

DIRACGrid/DIRACOS2#12