debian: Fix release package build

Since acrn-tools are not built when creating a release build, there are no
tool binaries to be installed. Generate the required debian/acrn-tools.install
file on the fly whenever a debug build is requested. This keeps this file
empty on a release build avoiding the resulting build errors about missing
files.

Additionally a package specific README.Debian file is added to explain this
behavior. It will be installed according to Debian packaging guidelines
at /usr/share/doc/acrn-tools/README.Debian.

Tracked-On: #8257
Signed-off-by: Helmut Buchsbaum <helmut.buchsbaum@opensource.tttech-industrial.com>

debian/acrn-tools.README.Debian

@@ -0,0 +1,7 @@
+acrn-tools for Debian
+---------------------
+
+Since acrn-tools cannot be provided for release builds, a virtually empty
+acrn-tools package indicates a release build package. As a consequence,
+the tools belonging to this package are only populated for debug builds.
+

debian/rules

@@ -146,6 +146,21 @@ else
   devnull = >/dev/null
 endif
 
+### dh_installdeb ############################################################
+
+# create acrntools.install for debug build
+ifeq ($(RELEASE),n)
+
+debian/acrn-tools.install: debian/acrn-tools.install.debug
+	@$(call echo-verbose)
+	@$(call echo-silent,CREATE $@)
+	$(Q)cp $< $@
+
+override_dh_install: debian/acrn-tools.install
+	$(Q)dh_install
+
+endif
+
 ### dh_installdeb ############################################################
 debian/acrn-hypervisor.postinst: debian/acrn-hypervisor.postinst.in
 	@$(call echo-verbose)
@@ -390,6 +405,7 @@ override_dh_auto_clean:
 	$(Q)rm -f debian/acrn-hypervisor.postinst
 	$(Q)rm -f debian/acrn-hypervisor.postrm
 	$(Q)rm -f debian/acrn-hypervisor.prerm
+	$(Q)rm -f debian/acrn-tools.install
 	$(Q)rm -f debian/acrn-hypervisor.templates
 	$(Q)rm -rf debian/acrn-board-inspector/build
 	$(Q)dh_auto_clean $(devnull)