libbpf: Support resizable hashtable

Add BPF_MAP_TYPE_RHASH to libbpf's map type name table and feature
probing so that libbpf-based tools can create and identify resizable
hash maps.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260605-rhash-v7-8-5b8e05f8630d@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

src/libbpf.c

@@ -192,6 +192,7 @@ static const char * const map_type_name[] = {
 	[BPF_MAP_TYPE_CGRP_STORAGE]		= "cgrp_storage",
 	[BPF_MAP_TYPE_ARENA]			= "arena",
 	[BPF_MAP_TYPE_INSN_ARRAY]		= "insn_array",
+	[BPF_MAP_TYPE_RHASH]			= "rhash",
 };
 
 static const char * const prog_type_name[] = {