Revert "Remove autotools build support"

This reverts commit 01ac32aab2109681abc58bb2f96a4ef4a7f0c6df.
diff --git a/RELEASING.md b/RELEASING.md
index 3a5a581..e3ef7b6 100644
--- a/RELEASING.md
+++ b/RELEASING.md
@@ -22,7 +22,7 @@
 
 4. Make sure you have correct date and new version at the top of NEWS file.
 
-5. Bump version in line 3 of meson.build.
+5. Bump version in line 3 of meson.build and configure.ac.
    Do a `meson test -Cbuild` so it both checks the tests and updates
    hb-version.h (use `git diff` to see if is really updated).