Fix makefile fuction

Makefile

@@ -3,9 +3,11 @@ VERSION = $(shell git describe | sed 's/-/./g')
 BRANCH = $(shell git branch --show-current)
 
 define rpm_eval
-shell rpm --eval '%{$(1)}'
+	rpm --eval '%{$(1)}'
 endef
 
+TARBALL_PATH = $(call rpm_eval,_sourcedir)/$(NAME)-$(VERSION).tar.gz
+
 .PHONY: name
 name:
 	@echo "$(NAME)"
@@ -14,7 +16,7 @@ name:
 version:
 	@echo "$(VERSION)"
 
-$(RPM_SOURCEDIR)/$(NAME)-%.tar.gz: *
+$(TARBALL_PATH): *
 	git archive --format=tar.gz \
 	            --output="$@" \
 	            --prefix="$(NAME)-$(VERSION)/" \
@@ -22,11 +24,11 @@ $(RPM_SOURCEDIR)/$(NAME)-%.tar.gz: *
 	            "$(BRANCH)"
 
 .PHONY: tarball
-tarball: $(RPM_SOURCEDIR)/$(NAME)-$(VERSION).tar.gz
+tarball: $(TARBALL_PATH)
 
 .PHONY: install
 install:
-	install --directory $(DESTDIR)$(call rpm_eval _sysconfdir)/netoik-rp
+	install --directory $(DESTDIR)$(call rpm_eval,_sysconfdir)/netoik-rp
-	install --target-directory=$(DESTDIR)$(call rpm_eval _sysconfdir)/netoik-rp/ conf/neotik-rp.conf
+	install --target-directory=$(DESTDIR)$(call rpm_eval,_sysconfdir)/netoik-rp/ conf/neotik-rp.conf
-	install --target-directory=$(DESTDIR)$(call rpm_eval _sysconfdir)/netoik-rp/ conf/ovh.ini
+	install --target-directory=$(DESTDIR)$(call rpm_eval,_sysconfdir)/netoik-rp/ conf/ovh.ini
-	install --target-directory=$(DESTDIR)$(call rpm_eval _unitdir)/ services/netoik-rp.service
+	install --target-directory=$(DESTDIR)$(call rpm_eval,_unitdir)/ services/netoik-rp.service