config: get_meta_section() misunderstands the beginning of metasection

For example, the line, "if [[ -n $no_proxy ]]; then" is misparsed
as the beginning of metasection because get_meta_section() misses
escaping of "|" unlike get_meta_section_files().
This patch adds necessary escape as "|" -> "\|".

Change-Id: Ic14b2ac167037c4f5db89492f0e8a4c5b13c7b6d
Closes-Bug: #1262960
diff --git a/lib/config b/lib/config
index c28072f..1678aec 100644
--- a/lib/config
+++ b/lib/config
@@ -35,7 +35,7 @@
 
     $CONFIG_AWK_CMD -v matchgroup=$matchgroup -v configfile=$configfile '
         BEGIN { group = "" }
-        /^\[\[.+|.*\]\]/ {
+        /^\[\[.+\|.*\]\]/ {
             if (group == "") {
                 gsub("[][]", "", $1);
                 split($1, a, "|");