[Makefile] more accurate deps for generating transitioning.ml

also put the target into `Makefile.generating`.

Makefile

@@ -397,13 +397,6 @@ LIB_CMO =\
 	src/libraries/utils/filepath \
 	src/libraries/utils/json
 
-GENERATED+= src/libraries/utils/json.ml src/libraries/stdlib/transitioning.ml
-
-src/libraries/stdlib/transitioning.ml: src/libraries/stdlib/transitioning.ml.in
-	rm -f $@
-	sed -e 's/@SPLIT_ON_CHAR@/$(SPLIT_ON_CHAR)/g' $< > $@
-	$(CHMOD_RO) $@
-
 NON_OPAQUE_DEPS+=\
   src/libraries/datatype/unmarshal_z \
   src/libraries/stdlib/integer

Makefile.generating

@@ -118,7 +118,16 @@ $(MACHDEP_PATH)/local_machdep.ml: \
 
 endif
 
+# transitioning.ml
 
+GENERATED+= src/libraries/utils/json.ml src/libraries/stdlib/transitioning.ml
+
+src/libraries/stdlib/transitioning.ml: \
+  src/libraries/stdlib/transitioning.ml.in \
+  Makefile.generating share/Makefile.config
+	rm -f $@
+	sed -e 's/@SPLIT_ON_CHAR@/$(SPLIT_ON_CHAR)/g' $< > $@
+	$(CHMOD_RO) $@
 
 ##################
 # Frama-C-config #