update_unicode.sh: move it into contrib/update-unicode

As it's used only by a tiny minority of the Git developer population,
this script does not belong into the main Git source directory.

Move it into contrib/ and adjust the paths to account for the new
location.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.gitignore

@@ -231,7 +231,6 @@
 /config.mak.autogen
 /config.mak.append
 /configure
-/unicode
 /tags
 /TAGS
 /cscope*

contrib/update-unicode/.gitignore

@@ -0,0 +1,3 @@
+uniset/
+UnicodeData.txt
+EastAsianWidth.txt

contrib/update-unicode/README

@@ -0,0 +1,20 @@
+TL;DR: Run update_unicode.sh after the publication of a new Unicode
+standard and commit the resulting unicode_widths.h file.
+
+The long version
+================
+
+The Git source code ships the file unicode_widths.h which contains
+tables of zero and double width Unicode code points, respectively.
+These tables are generated using update_unicode.sh in this directory.
+update_unicode.sh itself uses a third-party tool, uniset, to query two
+Unicode data files for the interesting code points.
+
+On first run, update_unicode.sh clones uniset from Github and builds it.
+This requires a current-ish version of autoconf (2.69 works per December
+2016).
+
+On each run, update_unicode.sh checks whether more recent Unicode data
+files are available from the Unicode consortium, and rebuilds the header
+unicode_widths.h with the new data. The new header can then be
+committed.

contrib/update-unicode/update_unicode.sh

@@ -5,11 +5,9 @@
 #Mn Nonspacing_Mark a nonspacing combining mark (zero advance width)
 #Cf Format          a format control character
 #
-UNICODEWIDTH_H=../unicode_width.h
-if ! test -d unicode; then
-	mkdir unicode
-fi &&
-( cd unicode &&
+cd "$(dirname "$0")"
+UNICODEWIDTH_H=$(git rev-parse --show-toplevel)/unicode_width.h
+(
 	if ! test -f UnicodeData.txt; then
 		wget http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
 	fi &&