Style: Fix code format scripts compat with non-GNU Unices

It's too hard to get compatibility between GNU and BSD sed,
so let's just use perl oneliners.

And improve it to also remove trailing tabs, not just spaces.

misc/scripts/black_format.sh

@@ -16,11 +16,9 @@ PY_FILES=$(find \( -path "./.git" \
 black -l 120 $PY_FILES
 
 git diff > patch.patch
-FILESIZE="$(stat -c%s patch.patch)"
-MAXSIZE=5
 
 # If no patch has been generated all is OK, clean up, and exit.
-if (( FILESIZE < MAXSIZE )); then
+if [ ! -s patch.patch ] ; then
     printf "Files in this commit comply with the black style rules.\n"
     rm -f patch.patch
     exit 0

misc/scripts/clang_format.sh

@@ -39,11 +39,9 @@ while IFS= read -rd '' f; do
 done
 
 git diff > patch.patch
-FILESIZE="$(stat -c%s patch.patch)"
-MAXSIZE=5
 
 # If no patch has been generated all is OK, clean up, and exit.
-if (( FILESIZE < MAXSIZE )); then
+if [ ! -s patch.patch ] ; then
     printf "Files in this commit comply with the clang-format style rules.\n"
     rm -f patch.patch
     exit 0

misc/scripts/file_format.sh

@@ -1,7 +1,13 @@
 #!/usr/bin/env bash
 
 # This script ensures proper POSIX text file formatting and a few other things.
-# This is supplementary to clang-black-format.sh, but should be run before it.
+# This is supplementary to clang_format.sh and black_format.sh, but should be
+# run before them.
+
+# We need dos2unix and recode.
+if [ ! -x "$(command -v dos2unix)" -o ! -x "$(command -v recode)" ]; then
+    printf "Install 'dos2unix' and 'recode' to use this script.\n"
+fi
 
 set -uo pipefail
 IFS=$'\n\t'
@@ -29,22 +35,17 @@ while IFS= read -rd '' f; do
     recode UTF-8 "$f" 2> /dev/null
     # Ensures that files have LF line endings.
     dos2unix "$f" 2> /dev/null
-    # Ensures that files do not contain a BOM.
-    sed -i '1s/^\xEF\xBB\xBF//' "$f"
-    # Ensures that files end with newline characters.
-    tail -c1 < "$f" | read -r _ || echo >> "$f";
     # Remove trailing space characters.
-    sed -z -i 's/\x20\x0A/\x0A/g' "$f"
+    # -l option handles newlines conveniently and seems to also get rid of BOMs.
+    perl -i -ple 's/\s*$//g' "$f"
     # Remove the character sequence "== true" if it has a leading space.
-    sed -z -i 's/\x20== true//g' "$f"
+    perl -i -pe 's/\x20== true//g' "$f"
 done
 
 git diff > patch.patch
-FILESIZE="$(stat -c%s patch.patch)"
-MAXSIZE=5
 
 # If no patch has been generated all is OK, clean up, and exit.
-if (( FILESIZE < MAXSIZE )); then
+if [ ! -s patch.patch ] ; then
     printf "Files in this commit comply with the formatting rules.\n"
     rm -f patch.patch
     exit 0