pre-commit: add error messages for style issues

Tools/astyle/pre-commit

@@ -31,7 +31,7 @@ if [ "$allownonascii" != "true" ] &&
 	test $(git diff --cached --name-only --diff-filter=A -z $against |
 	  LC_ALL=C tr -d '[ -~]\0' | wc -c) != 0
 then
-	echo "Error: Attempt to add a non-ascii file name."
+	echo "Pre-commit style error: Attempt to add a non-ascii file name."
 	echo
 	echo "This can cause problems if you want to work"
 	echo "with people on other platforms."
@@ -49,6 +49,7 @@ fi
 # If there are whitespace errors, print the offending file names and fail.
 git diff-index --check --cached $against --
 if [ $? -ne 0 ]; then
+	echo "Pre-commit style error: Whitespace issues"
         exit 1
 fi
 
@@ -58,6 +59,7 @@ do
         ./Tools/astyle/files_to_check_code_style.sh $i | xargs -n 1 -P 8 -I % ./Tools/astyle/check_code_style.sh %
         if [ $? -ne 0 ]
         then
+		echo "Pre-commit style error: Bad formatting according to astyle rules"
                 exit 1
         fi
 done