CLEANUP: Reapply ist.cocci with `--include-headers-for-types --recursive-includes`

Previous uses of `ist.cocci` did not add `--include-headers-for-types` and
`--recursive-includes` preventing Coccinelle seeing `struct ist` members of
other structs.

Reapply the patch with proper flags to further clean up the use of the ist API.

The command used was:

    spatch -sp_file dev/coccinelle/ist.cocci -in_place --include-headers --include-headers-for-types --recursive-includes --dir src/
diff --git a/src/h2.c b/src/h2.c
index 49a1252..5c3a6ae 100644
--- a/src/h2.c
+++ b/src/h2.c
@@ -402,7 +402,7 @@
 	lck = ck = -1; // no cookie for now
 	fields = 0;
 	for (idx = 0; list[idx].n.len != 0; idx++) {
-		if (!list[idx].n.ptr) {
+		if (!isttest(list[idx].n)) {
 			/* this is an indexed pseudo-header */
 			phdr = list[idx].n.len;
 		}
@@ -721,7 +721,7 @@
 
 	fields = 0;
 	for (idx = 0; list[idx].n.len != 0; idx++) {
-		if (!list[idx].n.ptr) {
+		if (!isttest(list[idx].n)) {
 			/* this is an indexed pseudo-header */
 			phdr = list[idx].n.len;
 		}
@@ -873,7 +873,7 @@
 	int i;
 
 	for (idx = 0; list[idx].n.len != 0; idx++) {
-		if (!list[idx].n.ptr) {
+		if (!isttest(list[idx].n)) {
 			/* This is an indexed pseudo-header (RFC7540#8.1.2.1) */
 			goto fail;
 		}