This directory stores modules which require external libraries to compile.
For example, m_regex_pcre requires the PCRE libraries.

To compile any of these modules first ensure you have the required dependencies
(read the online documentation at https://docs.inspircd.org/) and then symlink
the .cpp file from this directory into the parent directory (src/modules/).

Alternatively, use the command: ./configure --enable-extras=m_extra.cpp, which will
automatically take care of symlinking the module of that name and any headers it needs
from the extras directory. You can also use ./configure --list-extras to see what
modules are available, and whether they are enabled or not. You still are responsible
for resolving any external dependencies however (ie, PCRE, MySQL, GnuTLS, etc).

NOTE: Some modules require you to copy other dependencies too, such as a related header.
If you get missing header errors when building these modules, check that the header is
not within modules/extra before checking for external dependencies.