Fix version of live-build that is displayed by lb --version

Now we generate the VERSION file at install time or at package build time.

Makefile

@@ -40,7 +40,8 @@ build:
 install:
 	# Installing shared data
 	mkdir -p $(DESTDIR)/usr/share/live/build
-	cp -r data functions VERSION $(DESTDIR)/usr/share/live/build
+	cp -r data functions $(DESTDIR)/usr/share/live/build
+	sed -e 's/.*(\(.*\)).*/\1/; q' debian/changelog >$(DESTDIR)/usr/share/live/build/VERSION
 	cp -r share/* $(DESTDIR)/usr/share/live/build
 
 	# Installing executables

VERSION

@@ -1 +0,0 @@
-5.0~a11-1

debian/changelog

@@ -41,6 +41,8 @@ live-build (1:20161128) UNRELEASED; urgency=medium
   * Use a grub theme that integrates reasonably well with the current
     background picture.
   * Default for LB_UNION_FILESYSTEM is now "overlay" just like in live-boot.
+  * Update the way we generate the version of live-build that is displayed by
+    lb --version.
 
   [ Kristian Klausen ]
   * Include ext{3,4} journal size when calculating image size. Closes: #801712

debian/rules

@@ -1,11 +1,16 @@
 #!/usr/bin/make -f
 
+include /usr/share/dpkg/pkg-info.mk
+
 %:
 	dh $@
 
 override_dh_auto_install:
 	dh_auto_install -- DESTDIR=debian/live-build
 
+	# Update VERSION file
+	echo $(DEB_VERSION) >debian/live-build/usr/share/live/build/VERSION
+
 	# Removing unused files
 	rm -f debian/live-build/usr/share/doc/live-build/COPYING