configure: fix --mandir

--mandir points to the base dir of the man pages, so
we have to append our man section below given dir.
(transplanted from a8a4d5c9773893fa6978e5f9e1445d1e8185c24a)

Makefile.in

@@ -53,6 +53,11 @@ grep   := @@grep@@
 make   := @@make@@
 sed    := @@sed@@
 
+###############################################################################
+# Non-configure variables
+MAN_SECTION := 1
+MAN_SUBDIR := /man$(MAN_SECTION)
+
 ###############################################################################
 # Sanity checks
 
@@ -224,11 +229,11 @@ install-doc: $(DESTDIR)$(DOCDIR)
 	     $(install) -m 644 "$${doc_file}" "$(DESTDIR)$(DOCDIR)"; \
 	 done
 
-install-man: $(DESTDIR)$(MANDIR)
+install-man: $(DESTDIR)$(MANDIR)$(MAN_SUBDIR)
 	@echo "  INST   'ct-ng.1.gz'"
-	@$(install) -m 644 docs/ct-ng.1.gz "$(DESTDIR)$(MANDIR)"
+	@$(install) -m 644 docs/ct-ng.1.gz "$(DESTDIR)$(MANDIR)$(MAN_SUBDIR)"
 
-$(sort $(DESTDIR)$(BINDIR) $(DESTDIR)$(LIBDIR) $(DESTDIR)$(DOCDIR) $(DESTDIR)$(MANDIR)):
+$(sort $(DESTDIR)$(BINDIR) $(DESTDIR)$(LIBDIR) $(DESTDIR)$(DOCDIR) $(DESTDIR)$(MANDIR)$(MAN_SUBDIR)):
 	@echo "  MKDIR  '$@'"
 	@$(install) -m 755 -d "$@"
 

configure

@@ -408,7 +408,7 @@ printf "${VERSION}\n"
 [ -z "${BINDIR_set}" ] && BINDIR="${PREFIX}/bin"
 [ -z "${LIBDIR_set}" ] && LIBDIR="${PREFIX}/lib"
 [ -z "${DOCDIR_set}" ] && DOCDIR="${PREFIX}/share/doc"
-[ -z "${MANDIR_set}" ] && MANDIR="${PREFIX}/share/man/man1"
+[ -z "${MANDIR_set}" ] && MANDIR="${PREFIX}/share/man"
 
 # Install support files in our own sub-dir, so as not to mangle (system)
 # files and dirs, but only if not --local