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/types/checks.h b/include/types/checks.h
index b2be640..4b81770 100644
--- a/include/types/checks.h
+++ b/include/types/checks.h
@@ -17,7 +17,7 @@
 #include <import/ebpttree.h>
 
 #include <common/standard.h>
-#include <common/ist.h>
+#include <import/ist.h>
 #include <common/mini-clist.h>
 #include <common/regex.h>
 #include <common/buf.h>
diff --git a/include/types/connection.h b/include/types/connection.h
index 7357174..601e505 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -26,7 +26,7 @@
 #include <sys/socket.h>
 
 #include <haproxy/api-t.h>
-#include <common/ist.h>
+#include <import/ist.h>
 
 #include <types/listener.h>
 #include <types/obj_type.h>
diff --git a/include/types/fcgi-app.h b/include/types/fcgi-app.h
index f0fcdc7..7fb20ee 100644
--- a/include/types/fcgi-app.h
+++ b/include/types/fcgi-app.h
@@ -23,7 +23,7 @@
 #define _TYPES_HTTP_FCGI_H
 
 #include <haproxy/api-t.h>
-#include <common/ist.h>
+#include <import/ist.h>
 #include <common/fcgi.h>
 #include <common/mini-clist.h>
 #include <common/regex.h>
diff --git a/include/types/fd.h b/include/types/fd.h
index 0041d4d..7ec97bc 100644
--- a/include/types/fd.h
+++ b/include/types/fd.h
@@ -24,7 +24,7 @@
 
 #include <haproxy/api-t.h>
 #include <common/hathreads.h>
-#include <common/ist.h>
+#include <import/ist.h>
 #include <types/port_range.h>
 
 /* Direction for each FD event update */
diff --git a/include/types/http_htx.h b/include/types/http_htx.h
index 301034c..02b6b3b 100644
--- a/include/types/http_htx.h
+++ b/include/types/http_htx.h
@@ -28,7 +28,7 @@
 #include <common/buf.h>
 #include <common/http.h>
 #include <common/htx.h>
-#include <common/ist.h>
+#include <import/ist.h>
 
 /* Context used to find/remove an HTTP header. */
 struct http_hdr_ctx {
diff --git a/include/types/ring.h b/include/types/ring.h
index ac93c12..f3b3987 100644
--- a/include/types/ring.h
+++ b/include/types/ring.h
@@ -24,7 +24,7 @@
 
 #include <haproxy/api-t.h>
 #include <common/buf.h>
-#include <common/ist.h>
+#include <import/ist.h>
 
 /* The code below handles circular buffers with single-producer and multiple
  * readers (up to 255). The buffer storage area must remain always allocated.
diff --git a/include/types/sink.h b/include/types/sink.h
index 64b0bca..b10cb89 100644
--- a/include/types/sink.h
+++ b/include/types/sink.h
@@ -24,7 +24,7 @@
 
 #include <haproxy/api-t.h>
 #include <common/buffer.h>
-#include <common/ist.h>
+#include <import/ist.h>
 
 /* A sink may be of 4 distinct types :
  *   - file descriptor (such as stdout)
diff --git a/include/types/trace.h b/include/types/trace.h
index cd5e8be..ad9d7b6 100644
--- a/include/types/trace.h
+++ b/include/types/trace.h
@@ -24,7 +24,7 @@
 
 #include <haproxy/api-t.h>
 #include <common/buffer.h>
-#include <common/ist.h>
+#include <import/ist.h>
 #include <common/mini-clist.h>
 #include <types/sink.h>