Include THIRD-PARTY-NOTICES.txt in archive from 'make dist'

Resolves https://github.com/hengband/hengband/issues/3768 .

diff --git a/Makefile.am b/Makefile.am
index 023eed7..da64189 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -29,6 +29,7 @@ EXTRA_DIST = \
        readme.md \
        readme_angband \
        readme-eng.md \
+       THIRD-PARTY-NOTICES.txt \
        hengband.spec \
        $(visual_studio_files)