#4997 5.50.0: non-ascii characters in comment headers crash the build from source

[balducci]

hello,
building 5.50.0 from source on linux:

 -------------------------------------------------------------
 Maxima-version: "5.50.0"
 Maxima build date: "2026-08-19 16:11:00"
 Host type: "x86_64-unknown-linux-gnu"
 Lisp implementation type: "SBCL"
 Lisp implementation version: "2.6.7"
 User dir: "/home/balducci/.maxima"
 Temp dir: "/tmp"
 Object dir: "/home/balducci/.maxima/binary/5_50_0/sbcl/2_6_7"
 Frontend: false
 -------------------------------------------------------------

The build stops with:

----8<----
;; Compiling file /home/balducci/tmp/install-us-d/maxima-5.50.0/maxima-5.50.0/src/opr-util.lisp ...
*** - SYSTEM::LINE-COMMENT-READER: Invalid byte #xC2 in CHARSET:ASCII
      conversion
---->8----

Indeed, there are two non-ascii characters in the comment header of that file.
Turns out that the same problem was present also in other lisp sources.
The edits in the enclosed attachment allow the build to complete successfully for me.

Thanks for your valuable work
ciao
-gabriele