doc: autogenerate a list of authors and hall of fame

This adds a build-time option to automatically generate a list of
authors from git history, and includes it in the documentation by
reading the output from git in a Sphinx extension. When git isn't
available or the project source doesn't appear to be a git checkout, the
list is not generated and gracefully replaced with a message explaining
its absence.

Change-Id: I1e9634a90e84262aafd80590deba9875f4b71a3c
Signed-off-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/86350
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>

doc/collect-authors.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+if [ $# -ne 3 ]
+then
+    echo "Wrong number of arguments. Usage: $0 [authors|reviewers] outfile git_dir" >&2
+    exit 1
+fi
+
+case "$1" in
+    authors)
+        GROUP_ARGS="--group=author --group=trailer:Co-Authored-by --group=trailer:Co-Developed-by"
+        ;;
+    reviewers)
+        GROUP_ARGS="--group=trailer:Reviewed-by"
+        ;;
+    *)
+        echo "Unknown contributor kind: \"$1\"" >&2
+        exit 1
+        ;;
+esac
+OUTFILE="$2"
+# GIT_DIR is passed explicitly so we never need to guess where
+# the source directory is. It may be somewhere entirely different
+# from where meson is running us.
+GIT_DIR="$3"
+
+if ! command -v git >/dev/null
+then
+    echo "git not available" >&2
+    exit 1
+fi
+
+if [ ! -d "$GIT_DIR" ]
+then
+    echo "GIT_DIR ($GIT_DIR) does not exist" >&2
+    exit 1
+fi
+
+git --no-pager --git-dir="$GIT_DIR" shortlog --summary --numbered $GROUP_ARGS HEAD > "$OUTFILE"