Bug 1082537 - Instantbird Windows build busted due to missing nss symbols. r=florian

chat/nss-purple.def

@@ -0,0 +1,5 @@
+PK11_PubEncryptRaw
+PK11_PubDecryptRaw
+PK11_Verify
+PK11_RestoreContext
+PK11_SaveContextAlloc

im/confvars.sh

@@ -24,3 +24,6 @@ MOZ_APP_ID={33cb9019-c295-46dd-be21-8c4936574bee}
 if test "$OS_TARGET" = "WINNT" -o "$OS_TARGET" = "Darwin"; then
   MOZ_FOLD_LIBS=1
 fi
+if test "$OS_TARGET" = "WINNT"; then
+  NSS_EXTRA_SYMBOLS_FILE=../../../../chat/nss-purple.def
+fi