meson: add git-contrib target

meson.build

@@ -2269,3 +2269,11 @@ if git.found() and etags.found()
     input : all_files,
     command : [etags, '-o', '@OUTPUT@'] + all_files)
 endif
+
+if git.found()
+  meson_git_contrib_sh = find_program('tools/meson-git-contrib.sh')
+  custom_target(
+    'git-contrib',
+    output : 'git-contrib',
+    command : [meson_git_contrib_sh])
+endif

tools/meson-git-contrib.sh

@@ -0,0 +1,7 @@
+#!/bin/sh -e
+
+git shortlog -s `git describe --abbrev=0`.. | \
+    cut -c8- | \
+    sed 's/ / /g' | \
+    awk '{ print $$0 "," }' | \
+    sort -u