Merge xbps-src code to make it usable in a standalone mode.

The new xbps-src configuration file is `etc/conf` where you can
add your local overrides from defaults set via `etc/defaults.conf`.

To use this xbps-src, run these steps:

	$ make
	$ sudo make setup (to make chroot helper setgid)
	$ ./xbps-src ...

Makefile

@@ -0,0 +1,32 @@
+# xbps-packages top-level Makefile.
+#
+# MUTABLE VARIABLES
+PRIVILEGED_GROUP ?= xbuilder
+
+# INMUTABLE VARIABLES
+VERSION	= 112
+GITVER	:= $(shell git rev-parse --short HEAD)
+SHAREDIR = common/xbps-src/shutils
+LIBEXECDIR = common/xbps-src/libexec
+
+CHROOT_C = uchroot.c
+CHROOT_BIN = xbps-src-chroot-helper
+CFLAGS += -O2 -Wall -Werror
+
+.PHONY: all setup clean
+
+all:
+	sed -e "s|@@XBPS_SRC_VERSION@@|$(VERSION) ($(GITVER))|g"	\
+		${CURDIR}/common/xbps-src/xbps-src.sh > ${CURDIR}/xbps-src
+	$(CC) $(CFLAGS) ${LIBEXECDIR}/$(CHROOT_C) -o ${LIBEXECDIR}/$(CHROOT_BIN)
+	chmod 755 xbps-src
+	@echo
+	@echo "The chroot helper must be a setgid binary (4750) for the group '$(PRIVILEGED_GROUP)'."
+	@echo "Please run 'sudo make setup' to set appropiate permissions."
+
+setup:
+	chown root:$(PRIVILEGED_GROUP) $(LIBEXECDIR)/$(CHROOT_BIN)
+	chmod 4750 $(LIBEXECDIR)/$(CHROOT_BIN)
+
+clean:
+	rm -f xbps-src $(LIBEXECDIR)/$(CHROOT_BIN)