```
editors/nano: Make several port improvements
* Switch to https:// MASTER_SITES
* Use provided .xz for distribution file, saving: 50.5% / 1415kB
* Add LICENSE_FILE
* Remove CPPFLAGS/LDFLAGS variables, added 19 years ago when the port
was first created. [1] They are incorrectly (globally) scoped, no
longer necessary and incorrect for the ncurses:base case. Instead use
Uses/ncurses.mk variables and provide these to configure to ensure
includes/lib searches and linking are never mixed between base and
ports.
[1] ports r29979
Reviewed_by: danilo (maintainer)
Approved by: danilo (maintainer)
MFH: 2019Q2 (blanket: bugfix)
Differential_Revision: DXXXX
```