+=libcurl=
+ Provides HTTP request functionality.
+ Configure: `--with-http-libcurl-dir`
+ Minimum version: 7.18.2
+ Install on Debian: `apt-get install libcurl4-openssl-dev`
+
+=libevent=
+ Internal event loop support for the HTTP client.
+ Configure: `--with-http-libevent-dir`
+ Minimum version: none
+ Install on Debian: `apt-get install libevent-dev`
+
+=libicu=
+ Provides IDNA2003 and/or IDNA2008 support in URLs.
+ Configure: `--with-http-libicu-dir`
+ Minimum version: none
+ Install on Debian: `apt-get install libicu-dev`
+