Added native utilities to mount/umount/chroot via capabilities(7).

Three new helpers will now be installed into ${libexecdir}:
 - xbps-src-capchroot needs to have set CAP_SYS_CHROOT ep.
 - xbps-src-chroot-cap{,u}mount: needs to have set CAP_SYS_ADMIN ep.

That means that libcap and setcap(8) are now required to install
xbps-src and use it as normal user.

--HG--
extra : convert_revision : 586d6526079e085f86bf3e393459d429f6f0ef99

xbps-src/xbps-src.sh.in

@@ -163,8 +163,14 @@ set_defvars
 
 . $XBPS_SHUTILSDIR/common_funcs.sh
 
+if [ -n "$XBPS_USE_CAPCHROOT" ]; then
+	chroot_cmd="@@XBPS_INSTALL_LIBEXECDIR@@/xbps-src-capchroot"
+	unset sudo_cmd
+fi
+
 if [ "$(id -u)" -eq 0 ]; then
 	# disable sudo and fakeroot if uid==0
+	chroot_cmd="chroot"
 	unset sudo_cmd
 	if [ -n "$in_chroot" ]; then
 		unset fakeroot_cmd
@@ -172,10 +178,6 @@ if [ "$(id -u)" -eq 0 ]; then
 	fi
 fi
 
-if [ -n "$XBPS_USE_CAPCHROOT" ]; then
-	chroot_cmd="capchroot"
-fi
-
 # Main switch
 case "$target" in
 build|configure)