REORG: include: move ist.h from common/ to import/
Fortunately that file wasn't made dependent upon haproxy since it was
integrated, better isolate it before it's too late. Its dependency on
api.h was the result of the change from config.h, which in turn wasn't
correct. It was changed back to stddef.h for size_t and sys/types.h for
ssize_t. The recently added reference to MAX() was changed as it was
placed only to avoid a zero length in the non-free-standing version and
was causing a build warning in the hpack encoder.
diff --git a/include/common/h2.h b/include/common/h2.h
index 5654a76..32f0206 100644
--- a/include/common/h2.h
+++ b/include/common/h2.h
@@ -32,7 +32,7 @@
#include <haproxy/api.h>
#include <common/http-hdr.h>
#include <common/htx.h>
-#include <common/ist.h>
+#include <import/ist.h>
/* indexes of most important pseudo headers can be simplified to an almost