doc: move out merge script to tools

tools/libav-merge-next-commit

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+if [ "$1" != "merge" -a "$1" != "noop" ]; then
+    printf "Usage: $0 <merge|noop [REF_HASH]>\n"
+    exit 0
+fi
+
+[ "$1" = "noop" ] && merge_opts="-s ours"
+
+nextrev=$(git rev-list libav/master --not master --no-merges | tail -n1)
+if [ -z "$nextrev" ]; then
+    printf "Nothing to merge..\n"
+    exit 0
+fi
+printf "Merging $(git log -n 1 --oneline $nextrev)\n"
+git merge --no-commit $merge_opts --no-ff --log $nextrev
+
+if [ "$1" = "noop" -a -n "$2" ]; then
+    printf "\nThis commit is a noop, see $2\n" >> .git/MERGE_MSG
+fi
+
+printf "\nMerged-by: $(git config --get user.name) <$(git config --get user.email)>\n" >> .git/MERGE_MSG