Bug 402773, Verify the list of public header files in NSS 3.12

make sdb.h and sftkdbt.h private
r=rrelyea

security/nss/lib/softoken/manifest.mn

@@ -58,8 +58,6 @@ EXPORTS = \
 	pkcs11t.h \
 	pkcs11n.h \
 	pkcs11u.h \
-	sdb.h \
-	sftkdbt.h \
 	$(NULL)
 
 PRIVATE_EXPORTS = \
@@ -71,6 +69,8 @@ PRIVATE_EXPORTS = \
 	softoken.h \
 	softoknt.h \
 	softkver.h \
+	sdb.h \
+	sftkdbt.h \
 	$(NULL)
 
 CSRCS = \