cleanlog, reports.mk: factor the script out

Sometimes REPORT=1 just wasn't passed to make, and the build.log
saved is noisy and harder to compare through diff(1); let's move
the implementation out of the makefile and into a standalone
script so it can be reused like this:

  BUILDDIR=$(sed -rn "s/^mki-image-scripts: export GLOBAL_BUILDDIR='(.*)'$/\1/p" build/build.log
  bin/cleanlog < build/build.log > build/reports/clean.log

See "export GLOBAL_BUILDDIR=" line in the particular log
(grabbing that one from stdin is not exactly trivial though).

bin/cleanlog

@@ -0,0 +1,24 @@
+#!/bin/sh
+# try making build logs more diffable
+# see also reports.mk
+
+[ -n "$BUILDDIR" ] || exit 1
+
+sed -r \
+	-e "s,$BUILDDIR,,g" \
+	-e '/\/var\/lib\/apt\/lists/d' \
+	-e 's/... .. ..:..:..//g' \
+	-e 's/\[[0-9]+\]//g' \
+	-e '/^(Reading Package Lists|Building Dependency Tree)/d' \
+	-e '/^(Fetched|Need to get|After unpacking) /d' \
+	-e '/^(Preparing packages for installation|Done\.)/d' \
+	-e '/^hsh(|-(initroot|install|fakedev|(mk|rm)chroot|run)): /d' \
+	-e '/^(hasher-priv|mkaptbox|(mk|rm)dir): /d' \
+	-e '/^mki-((invalidate-|)cache|check-obsolete|prepare): /d' \
+	-e '/^(mode of|changed (group|ownership)|removed) /d' \
+	-e '/^chroot\/.in\//d' \
+	-e '/ has started executing\.$/d' \
+	-e '/\/var\/log\/apt\.log$/d' \
+	-e '/\/usr\/share\/apt\/scripts\/log\.lua/d' \
+	-e '/\.rpm$/d' \
+	-e "/' -> '/d"

reports.mk

@@ -28,26 +28,7 @@ reports/prep:
 # try to drop common noise rendering diff(1) mostly useless
 reports/cleanlog: reports/prep
 	@OUT="$(REPORTDIR)/$(@F).log"; \
-	sed -r \
+	BUILDDIR="$(BUILDDIR)" cleanlog < $(BUILDLOG) > "$$OUT" \
-		-e 's,$(BUILDDIR),,g' \
-		-e '/\/var\/lib\/apt\/lists/d' \
-		-e 's/... .. ..:..:..//g' \
-		-e 's/\[[0-9]+\]//g' \
-		-e '/^(Reading Package Lists|Building Dependency Tree)/d' \
-		-e '/^(Fetched|Need to get|After unpacking) /d' \
-		-e '/^(Preparing packages for installation|Done\.)/d' \
-		-e '/^hsh(|-(initroot|install|fakedev|(mk|rm)chroot|run)): /d' \
-		-e '/^(hasher-priv|mkaptbox|(mk|rm)dir): /d' \
-		-e '/^mki-((invalidate-|)cache|check-obsolete|prepare): /d' \
-		-e '/^(mode of|changed (group|ownership)|removed) /d' \
-		-e '/^chroot\/.in\//d' \
-		-e '/ has started executing\.$$/d' \
-		-e '/\/var\/log\/apt\.log$$/d' \
-		-e '/\/usr\/share\/apt\/scripts\/log\.lua/d' \
-		-e '/\.rpm$$/d' \
-		-e "/' -> '/d" \
-		< $(BUILDLOG) \
-		> "$(REPORTDIR)/$(@F).log" \
 	&& echo "** diffable log: $$OUT" $(SHORTEN)
 
 reports/scripts: reports/prep