Move libvpx from DEPS to src

third_party/libvpx/source/libvpx/tools/author_first_release.sh

Index: third_party/libvpx/source/libvpx/tools/author_first_release.sh
diff --git a/third_party/libvpx/source/libvpx/tools/author_first_release.sh b/third_party/libvpx/source/libvpx/tools/author_first_release.sh
new file mode 100755
index 0000000000000000000000000000000000000000..7b0b79721253ee5f77586c276e22f951389490e5
--- /dev/null
+++ b/third_party/libvpx/source/libvpx/tools/author_first_release.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+##
+## List the release each author first contributed to.
+##
+## Usage: author_first_release.sh [TAGS]
+##
+## If the TAGS arguments are unspecified, all tags reported by `git tag`
+## will be considered.
+##
+tags=${@:-$(git tag)}
+for tag in $tags; do
+  git shortlog -n -e -s $tag |
+      cut -f2- |
+      awk "{print \"${tag#v}\t\"\$0}"
+done | sort -k2  | uniq -f2