linux-rl-sdl20 port and distfile fetching

I am hopeful at migrating some of the 32-bit Linux games I maintain to 
rl9 to take advantage of security and bug fixes.  As they require SDL 
1.2, they could possibly run with the sdl12-compat library.  I have not 
tested this as of yet.  In fact, I have not tested the port other than 
building, but I am sure it works.  :D  I do not want to continue down 
this path if it is totally wrong.

However, I did create a port for linux-rl9-sdl20, which would be needed 
first.  This required changes to Uses/linux.mk due to how packages are 
stored on the Rocky Linux site.  The filename starts with "SDL2-2.26.0"
while the directory it inhabits uses a lowercase "s".  The patch worked 
for me under poudriere to fetch the base rl9 files and the new port by 
always making the subdirectory lowercase.

Both patches are here:  https://people.freebsd.org/~scf/linux-rl9/

Sean
-- 
scf@FreeBSD.org