MINOR: htx: switch to case sensitive search of lower case header names

Now that we know that htx only contains lower case header names, there
is no need anymore for looking them up in a case-insensitive manner.

Note that http_find_header() still does it because header names to
compare against may come from everywhere there.
diff --git a/src/proto_htx.c b/src/proto_htx.c
index c613e72..c22908a 100644
--- a/src/proto_htx.c
+++ b/src/proto_htx.c
@@ -4609,7 +4609,7 @@
 		n = htx_get_blk_name(htx, blk);
 		v = htx_get_blk_value(htx, blk);
 
-		if (isteqi(n, ist("Pragma"))) {
+		if (isteq(n, ist("pragma"))) {
 			if (v.len >= 8 && strncasecmp(v.ptr, "no-cache", 8) == 0) {
 				pragma_found = 1;
 				continue;
@@ -4618,13 +4618,13 @@
 
 		/* Don't use the cache and don't try to store if we found the
 		 * Authorization header */
-		if (isteqi(n, ist("Authorization"))) {
+		if (isteq(n, ist("authorization"))) {
 			txn->flags &= ~TX_CACHEABLE & ~TX_CACHE_COOK;
 			txn->flags |= TX_CACHE_IGNORE;
 			continue;
 		}
 
-		if (!isteqi(n, ist("Cache-control")))
+		if (!isteq(n, ist("cache-control")))
 			continue;
 
 		/* OK, right now we know we have a cache-control header */
@@ -4697,14 +4697,14 @@
 		n = htx_get_blk_name(htx, blk);
 		v = htx_get_blk_value(htx, blk);
 
-		if (isteqi(n, ist("Pragma"))) {
+		if (isteq(n, ist("pragma"))) {
 			if ((v.len >= 8) && strncasecmp(v.ptr, "no-cache", 8) == 0) {
 				txn->flags &= ~TX_CACHEABLE & ~TX_CACHE_COOK;
 				return;
 			}
 		}
 
-		if (!isteqi(n, ist("Cache-control")))
+		if (!isteq(n, ist("cache-control")))
 			continue;
 
 		/* OK, right now we know we have a cache-control header */