fix bin/sort.gitignore.sh and bin/sgi.sh

We added ._.DS_Store to `.gitignore`, and generalized the `/archive/historic/`
year sub-directories into a single pattern line.

We fix `bin/sgi.sh` to properly sort, canonically, `.gitignore` files
including `._.DS_Store` lines.  The tool now stories stdin content
into a temporary file, then prints 6 classes of files from the
temporary file to stdout.

Changed `bin/sgi.sh` VERSION from "1.1.3 2024-08-18"
to "1.2 2024-09-05".

Fixed a bug in `bin/sort.gitignore.sh` that prevented it from
finding the `bin/sgi.sh` tool.

Changed `bin/sort.gitignore.sh` VERSION from "1.1.8 2024-07-28"
to "1.2 2024-09-05".

Performed `make sort_gitignore` to test the above under macOS.

NOTE: The above canonically sorted:

- 2004/hibachi/.gitignore
- 2005/mynx/.gitignore
- 2011/vik/.gitignore
- 2013/dlowe/.gitignore
- 2020/otterness/.gitignore

2005/mynx/.gitignore

@@ -9,7 +9,7 @@ mynx.alt
 mynx.alt2
 mynx.orig
 prog.orig
-source/config.*
-source/makefile
 source-alt/config.*
 source-alt/makefile
+source/config.*
+source/makefile