bug 354835 fix typo - this BOOTSTRAP_core should be BOOTSTRAP_necko, so

that _core doesn't become empty on the next assignment
r=bsmedberg

client.mk

@@ -205,7 +205,7 @@ LOCALES_core :=                                 \
   dom                                           \
   $(NULL)
 
-BOOTSTRAP_core :=                               \
+BOOTSTRAP_necko :=                              \
   mozilla/browser/config/version.txt            \
   mozilla/mail/config/version.txt               \
   mozilla/calendar/sunbird/config/version.txt   \