devtools: fix symbol check when adding experimental section

The incriminated commit did relax the condition to catch all sections
but dropped the + removal which can trigger false detection of the
special EXPERIMENTAL section when adding symbols and the section in the
same patch.

Fixes: 7281cf520f ("devtools: relax rule for identifying symbol section")
Cc: stable@dpdk.org

Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>

devtools/check-symbol-change.sh

@@ -31,6 +31,7 @@ build_map_changes()
 		# Triggering this rule sets in_sec to 1, which actives the
 		# symbol rule below
 		/^.*{/ {
+			gsub("+", "");
 			if (in_map == 1) {
 				sec=$(NF-1); in_sec=1;
 			}