www/h2o*: meld devel flavour into main port

- upstream has indicated there will be no more versioned releases
- only master branch updates
- all remaining consumers of libh2o have moved to alternatives

MOVED

@@ -3055,3 +3055,4 @@ lang/swi-pl|lang/swipl|2024-03-17|Port renamed on request
 devel/rubygem-with_advisory_lock|devel/rubygem-with_advisory_lock61|2024-03-18|Port renamed to follow naming convention
 emulators/cpmemu||2024-03-19|Has expired: BROKEN on all versions since last year
 devel/grpc142||2024-03-20|Has expired: Please use devel/grpc instead
+www/h2o-devel|www/h2o|2024-03-23|Upstream no longer supports releases, this port is folded into www/h2o instead

www/Makefile

@@ -240,7 +240,6 @@
     SUBDIR += gwsocket
     SUBDIR += h2c
     SUBDIR += h2o
-    SUBDIR += h2o-devel
     SUBDIR += habari
     SUBDIR += hiawatha
     SUBDIR += hiawatha-monitor