Add missing GIT_BEGIN_DECL and GIT_END_DECL to indexer header
diff --git a/include/git2/indexer.h b/include/git2/indexer.h
index 6c31956..2852d7e 100644
--- a/include/git2/indexer.h
+++ b/include/git2/indexer.h
@@ -4,6 +4,8 @@
#include "git2/common.h"
#include "git2/oid.h"
+GIT_BEGIN_DECL
+
/**
* This is passed as the first argument to the callback to allow the
* user to see the progress.
@@ -63,5 +65,6 @@ GIT_EXTERN(const git_oid *) git_indexer_hash(git_indexer *idx);
*/
GIT_EXTERN(void) git_indexer_free(git_indexer *idx);
+GIT_END_DECL
#endif