[source] include/download.mk: Use -7e compression instead of -6 by default

[LEDE Commits]

jow pushed a commit to source.git, branch master:
https://git.lede-project.org/cbc80805bd5f957cd5fad83c18adfa66f80a7d5e

commit cbc80805bd5f957cd5fad83c18adfa66f80a7d5e
Author: Daniel Engberg <daniel.engberg.lists at pyret.net>
AuthorDate: Tue Oct 4 06:36:53 2016 -0500

    include/download.mk: Use -7e compression instead of -6 by default
    
    Adds a slightly higher compression level to xz by default which roughly raises memory usage from 100MiB to about 200MiB during compression, about 10MiB for decompression. (Source: xz manpage)
    
    Signed-off-by: Daniel Engberg <daniel.engberg.lists at pyret.net>
---
 include/download.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/download.mk b/include/download.mk
index 227612d..2797e90 100644
--- a/include/download.mk
+++ b/include/download.mk
@@ -35,7 +35,7 @@ endef
 # code for creating tarballs from cvs/svn/git/bzr/hg/darcs checkouts - useful for mirror support
 dl_pack/bz2=$(TAR) --owner=0 --group=0 --sort=name $$$${TAR_TIMESTAMP:+--mtime="$$$$TAR_TIMESTAMP"} -cjf $(1) $(2)
 dl_pack/gz=$(TAR) --owner=0 --group=0 --sort=name $$$${TAR_TIMESTAMP:+--mtime="$$$$TAR_TIMESTAMP"} -c $(2) | gzip -nc > $(1)
-dl_pack/xz=$(TAR) --owner=0 --group=0 --sort=name $$$${TAR_TIMESTAMP:+--mtime="$$$$TAR_TIMESTAMP"} -c $(2) | xz -zc > $(1)
+dl_pack/xz=$(TAR) --owner=0 --group=0 --sort=name $$$${TAR_TIMESTAMP:+--mtime="$$$$TAR_TIMESTAMP"} -c $(2) | xz -zc -7e > $(1)
 dl_pack/unknown=echo "ERROR: Unknown pack format for file $(1)"; false
 define dl_pack
 	$(if $(dl_pack/$(call ext,$(1))),$(dl_pack/$(call ext,$(1))),$(dl_pack/unknown))