put cachedir in environmental variable

XBMK_CACHE is now used, instead of hardcoding cache/

this is exported initialised to cache/, if unset.
this means you can set your own directory, and it means
./update release will use the same directory.

this means bandwidth wastage is further avoided.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/git.sh

@@ -37,7 +37,7 @@ fetch_project()
 
 clone_project()
 {
-	loc="cache/repo/$project" && singletree "$project" && \
+	loc="$XBMK_CACHE/repo/$project" && singletree "$project" && \
 	    loc="src/$project"
 
 	printf "Downloading project '%s' to '%s'\n" "$project" "$loc"
@@ -62,8 +62,9 @@ git_prep()
 	[ "$project" = "coreboot" ] && [ -n "$xtree" ] && [ $# -gt 2 ] && \
 	    [ "$xtree" != "$tree" ] && link_crossgcc "$_loc"
 
-	[ "$XBMK_RELEASE" = "y" ] && [ "$_loc" != "cache/repo/$project" ] \
-	    && rmgit "$tmpgit"
+	[ "$XBMK_RELEASE" = "y" ] && \
+	    [ "$_loc" != "$XBMK_CACHE/repo/$project" ] && \
+		rmgit "$tmpgit"
 
 	move_repo "$_loc"
 }
@@ -106,8 +107,8 @@ tmpclone()
 	repofail="n"
 
 	[ $# -lt 6 ] || rm -Rf "$3" || $err "git retry: !rm $3 ($1)"
-	repodir="cache/repo/${1##*/}" && [ $# -gt 5 ] && repodir="$3"
-	x_ mkdir -p "cache/repo"
+	repodir="$XBMK_CACHE/repo/${1##*/}" && [ $# -gt 5 ] && repodir="$3"
+	mkdir -p "$XBMK_CACHE/repo" || $err "!rmdir $XBMK_CACHE/repo"
 	if [ -d "$repodir" ] && [ $# -lt 6 ]; then
 		git -C "$repodir" pull || sleep 3 || git -C "$repodir" pull \
 		    || sleep 3 || git -C "$repodir" pull || :