[FAB-9281] Update check_license.sh, ^build/ -> ^.build/

Given renaming of build/ to .build/, update the license
checking script to refer to the new name.

Change-Id: I20eb42462c9b45b7a241ada29f5abfd635fbc99d
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>

Author: rpjday

scripts/check_license.sh

@@ -9,7 +9,7 @@ function filterExcludedFiles {
   CHECK=`echo "$CHECK" | grep -v .png$ | grep -v .rst$ | grep -v ^.git/ \
   | grep -v .pem$ | grep -v .block$ | grep -v .tx$ | grep -v ^LICENSE$ | grep -v _sk$ \
   | grep -v .key$ | grep -v \\.gen.go$ | grep -v ^Gopkg.lock$ | grep -v 'testdata/' \
-  | grep -v .md$ | grep -v ^vendor/ | grep -v ^build/ | grep -v .pb.go$ | sort -u`
+  | grep -v .md$ | grep -v ^vendor/ | grep -v ^.build/ | grep -v .pb.go$ | sort -u`
 }
 
 CHECK=$(git diff --name-only --diff-filter=ACMRTUXB HEAD)