This compile-time option allows to ask Git to load libcurl dynamically
at runtime.
Together with a follow-up patch that optionally overrides the file name
depending on the `http.sslBackend` setting, this kicks open the door for
installing multiple libcurl flavors side by side, and load the one
corresponding to the (runtime-)configured SSL/TLS backend.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fc3c59d8af