build: include package directory in sha256sums when running on buildbot

In order to be able to better compare files to sync in the future, include
all BIN_DIR subdirectories in the checksum calculation.

To not break existing applications, restrict the recursive checksumming to
CONFIG_BUILDBOT for now.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

Makefile

@@ -85,7 +85,7 @@ prereq: $(target/stamp-prereq) tmp/.prereq_packages
 	fi
 
 checksum: FORCE
-	$(call sha256sums,$(BIN_DIR))
+	$(call sha256sums,$(BIN_DIR),$(CONFIG_BUILDBOT))
 
 diffconfig: FORCE
 	mkdir -p $(BIN_DIR)

rules.mk

@@ -390,8 +390,9 @@ endef
 
 # Calculate sha256sum of any plain file within a given directory
 # $(1) => Input directory
+# $(2) => If set, recurse into subdirectories
 define sha256sums
-	(cd $(1); find . -maxdepth 1 -type f -not -name 'sha256sums' -printf "%P\n" | sort | \
+	(cd $(1); find . $(if $(2),,-maxdepth 1) -type f -not -name 'sha256sums' -printf "%P\n" | sort | \
 		xargs -r $(STAGING_DIR_HOST)/bin/mkhash -n sha256 | sed -ne 's!^\(.*\) \(.*\)$$!\1 *\2!p' > sha256sums)
 endef