Note that pkgconfig is now needed, and has been for a few releases.

changes/new_requirement_pkgconfig

@@ -0,0 +1,5 @@
+  o New dependencies:
+    - To build with zstd and lzma support, Tor now requires the
+      pkg-config tool at build time. (This requirement was new in
+      0.3.1.1-alpha, but was not noted at the time. Noting it here to
+      close ticket 22623.)