perf tools: Update copy of libbpf's hashmap.c

To pick the changes in:

  a3e7e6b1 ("libbpf: Remove HASHMAP_INIT static initialization helper")

That don't entail any changes in tools/perf.

This addresses this perf build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/perf/util/hashmap.h tools/lib/bpf/hashmap.h

Not a kernel ABI, its just that this uses the mechanism in place for
checking kernel ABI files drift.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/hashmap.h

@@ -80,16 +80,6 @@ struct hashmap {
 	size_t sz;
 };
 
-#define HASHMAP_INIT(hash_fn, equal_fn, ctx) {	\
-	.hash_fn = (hash_fn),			\
-	.equal_fn = (equal_fn),			\
-	.ctx = (ctx),				\
-	.buckets = NULL,			\
-	.cap = 0,				\
-	.cap_bits = 0,				\
-	.sz = 0,				\
-}
-
 void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
 		   hashmap_equal_fn equal_fn, void *ctx);
 struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,