reduce max file size back to 684k in sanity check

This is because CodegenCpp.tpl has been split meanwhile.

Makefile.common

@@ -412,7 +412,7 @@ git-clean:
 	git clean -fdx
 
 git-sanity-check: git-clean
-	test "./Compiler/boot/bootstrap-sources.tar.xz" = "`find . -type f -size +800k | grep -v 3rdParty`"
+	test "./Compiler/boot/bootstrap-sources.tar.xz" = "`find . -type f -size +684k | grep -v 3rdParty`"
 	for commit in `git rev-list origin/master..HEAD`; do \
 	  (! git ls-tree --name-only -r $$commit | egrep "(.*[.](html|png|svg|o|so|la|stamp|a|dll|exe|cab|lnk|msi|log|class|jar|pyc|db|zip|DS_Store|pdf|tex|md5|dep)$$)|SimulationRuntime/cpp/Doc") || exit 1; \
 	done