feat: support the mailmap file in mkreleasenotes

This will use either the mailmap file in the current repo, or the mailmap file
in the target repo, when generating the contributor stats.

bin/mkreleaselog

@@ -33,15 +33,22 @@ AUTHORS=(
 
 NL=$'\n'
 
+ROOT_DIR="$(git rev-parse --show-toplevel)"
+
 msg() {
     echo "$*" >&2
 }
 
 statlog() {
-    rpath="$GOPATH/src/$1"
-    start="${2:-}"
-    end="${3:-HEAD}"
-    git -C "$rpath" log --shortstat --no-merges --pretty="tformat:%H%n%aN%n%aE" "$start..$end" | while 
+    local rpath="$GOPATH/src/$1"
+    local start="${2:-}"
+    local end="${3:-HEAD}"
+    local mailmap_file="$rpath/.mailmap"
+    if ! [[ -e "$mailmap_file" ]]; then
+        mailmap_file="$ROOT_DIR/.mailmap"
+    fi
+
+    git -C "$rpath" -c mailmap.file="$mailmap_file" log --use-mailmap --shortstat --no-merges --pretty="tformat:%H%n%aN%n%aE" "$start..$end" | while 
         read hash
         read name
         read email