pkg-infra: add hook to log timing of steps

The timing information is stored in the file $(O)/build-time.log

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pkg-generic.mk

@@ -44,6 +44,17 @@ define step_end
 	$(foreach hook,$(GLOBAL_INSTRUMENTATION_HOOKS),$(call $(hook),end,$(1),$($(PKG)_NAME))$(sep))
 endef
 
+#######################################
+# Actual steps hooks
+
+# Time steps
+define step_time
+	printf "%s:%-5.5s:%-20.20s: %s\n"           \
+	       "$$(date +%s)" "$(1)" "$(2)" "$(3)"  \
+	       >>"$(BUILD_DIR)/build-time.log"
+endef
+GLOBAL_INSTRUMENTATION_HOOKS += step_time
+
 ################################################################################
 # Implicit targets -- produce a stamp file for each step of a package build
 ################################################################################