Break up headers into constituent parts
This is part of a broader change to make header files better represent the
dependencies between one another (see
https://github.com/jemalloc/jemalloc/issues/533). It breaks up component headers
into smaller parts that can be made to have a simpler dependency graph.
For the autogenerated headers (smoothstep.h and size_classes.h), no splitting
was necessary, so I didn't add support to emit multiple headers.
diff --git a/include/jemalloc/internal/ql.h b/include/jemalloc/internal/ql.h
index 1834bb8..424485c 100644
--- a/include/jemalloc/internal/ql.h
+++ b/include/jemalloc/internal/ql.h
@@ -1,3 +1,6 @@
+#ifndef JEMALLOC_INTERNAL_QL_H
+#define JEMALLOC_INTERNAL_QL_H
+
/* List definitions. */
#define ql_head(a_type) \
struct { \
@@ -79,3 +82,5 @@
#define ql_reverse_foreach(a_var, a_head, a_field) \
qr_reverse_foreach((a_var), ql_first(a_head), a_field)
+
+#endif /* JEMALLOC_INTERNAL_QL_H */