Add target to build package for Gentoo

Makefile

@@ -15,7 +15,8 @@ SUPPORTED := ubuntu-20.04 \
 	     debian-11 \
 	     rockylinux-8 \
 	     rockylinux-9 \
-	     oraclelinux-7
+	     oraclelinux-7 \
+	     gentoo
 
 ##
 # These targets are the main ones to use for most things.
@@ -28,6 +29,12 @@ SUPPORTED := ubuntu-20.04 \
 .PHONY: package-all
 all: $(foreach distro_release, $(SUPPORTED), package-$(distro_release))
 
+# Gentoo package (tar.gz) creation
+.PHONY: package-gentoo
+package-gentoo:
+	mkdir -p $(BUILD_DIR)/gentoo
+	tar --transform "s,^\.,$(PACKAGE_NAME)-$(VERSION)," -acjf $(BUILD_DIR)/gentoo/$(PACKAGE_NAME)-$(VERSION).tar.bz2 --exclude $(BUILD_DIR) .
+
 
 # Create a deb package
 .PHONY: package-%
@@ -42,7 +49,6 @@ package-%:
 	    --user $(shell id -u):$(shell id -g) \
 	    "$(DISTRO)-packager:$(RELEASE)"
 
-
 # Create a tarball
 tgz:
 	rm -rf $(BUILD_DIR)/tgz/root