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

bin/sort.gitignore.sh

@@ -101,7 +101,7 @@ shopt -s globstar	# enable ** to match all files and zero or more directories an
 
 # set variables referenced in the usage message
 #
-export VERSION="1.1.8 2024-07-28"
+export VERSION="1.2 2024-09-05"
 NAME=$(basename "$0")
 export NAME
 export V_FLAG=0
@@ -272,15 +272,15 @@ export BIN_DIR="bin"
 # verify that the bin/sgi.sh tool is executable
 #
 export SGI_TOOL="$BIN_DIR/sgi.sh"
-if [[ ! -e $SGI_TOOL.sh ]]; then
+if [[ ! -e $SGI_TOOL ]]; then
     echo  "$0: ERROR: bin/sgi.sh does not exist: $SGI_TOOL.sh" 1>&2
     exit 5
 fi
-if [[ ! -f $SGI_TOOL.sh ]]; then
+if [[ ! -f $SGI_TOOL ]]; then
     echo  "$0: ERROR: bin/sgi.sh is not a regular file: $SGI_TOOL.sh" 1>&2
     exit 5
 fi
-if [[ ! -x $SGI_TOOL.sh ]]; then
+if [[ ! -x $SGI_TOOL ]]; then
     echo  "$0: ERROR: bin/sgi.sh is not an executable file: $SGI_TOOL.sh" 1>&2
     exit 5
 fi