Add missing headers to the modulemap

Author: tiennou

ObjectiveGit.modulemap

@@ -57,12 +57,14 @@ framework module ObjectiveGit {
 	header "git2/sys/hashsig.h"
 	header "git2/sys/index.h"
 	header "git2/sys/mempack.h"
+	header "git2/sys/merge.h"
 	header "git2/sys/odb_backend.h"
 	header "git2/sys/refdb_backend.h"
 	header "git2/sys/reflog.h"
 	header "git2/sys/refs.h"
 	header "git2/sys/repository.h"
 	header "git2/sys/transport.h"
+	header "git2/sys/time.h"
 	header "git2/cred_helpers.h"
 	header "git2/sys/openssl.h"
 	header "git2/sys/stream.h"