build-aux/Makefile.am (suppliers.mk): Regenerate when any sources change

This should have been done many years ago.  This will determine if any of
the dependencies have changed for the included suppliers.mk and regenerate
it as needed, without the developer having to do so manually when imports
change.

RELEASES.md

@@ -39,8 +39,11 @@ Build System
   accommodate liza-proguic's step-level package generation.
 - Step-level program packages are now properly accounted for as dependencies
   for builds.
-- `supplier.mk` generation will no longer be verbose (it'll instead be only
-  one line), which makes it more amenable to more frequent regeneration.
+- `supplier.mk` is now automatically regenerated when source files
+  change.  This previously needed to be done manually when imports changed.
+  - `supplier.mk` generation will no longer be verbose (it'll instead be
+    only one line), which makes it more amenable to more frequent
+    regeneration.
 
 
 v17.7.0 (2020-12-09)

build-aux/Makefile.am

@@ -82,6 +82,13 @@ package_dfns_pkgs = $(shell \
 )
 package_dfns_xmlos = $(patsubst %.xml, %.xmlo, $(package_dfns_pkgs))
 
+# Dependencies for suppliers.mk.
+src_suppliersmk = $(src_common) \
+                  $(shell find $(path_suppliers) ui/package ui/map rater/core -name '*.xml') \
+                  $(program_fragments) \
+                  ui/program.xml \
+                  ui/package-dfns.xml
+
 compiled_suppliers := $(src_suppliers:.xml=.xmlo)
 linked_suppliers   := $(src_suppliers:.xml=.xmle)
 
@@ -258,11 +265,12 @@ clean:
 		| sed 's/\.csvm$$/\.xml/; s/\.dat$$/\.xml/' \
 		| xargs rm -fv
 
-# generates a Makefile that will properly build all package dependencies; note
-# that territory and rate packages also have includes; see top of this file for
-# an explanation
-suppliers.mk: $(path_ui)/package-dfns.xml
-	$(ant) -q pkg-dep
+# Generates a Makefile that will properly build all package
+# dependencies.  The redirect of ant to /dev/null is because it's still too
+# noisy even with -q---the "BUILD SUCCESSFUL" line is confusing, considering
+# it's merely a small part of a broader build.
+suppliers.mk: $(src_suppliersmk)
+	$(ant) -q pkg-dep >/dev/null
 	find $(path_ui)/program/ -name '*.dep' | xargs cat $(path_ui)/program.dep | sort -u \
 	  > $(path_ui)/package-dfns.dep
 	$(RM) $(path_ui)/program.dep