libbpf: fix -Wformat warnings from format/argument type mismatches

Building libbpf with -Wall (as happens via bpftool's bootstrap build)
surfaces ~120 -Wformat warnings where pr_warn/pr_debug format specifiers
don't match their argument types: %d for __u32/Elf64_Word, %u for signed
ints, %zd for size_t, %ld for unsigned long, and %x/%lx/%llx applied to
signed values.

Match each specifier to its argument's type where a correctly-signed
specifier exists (%d<->%u, %ld->%lu, %zd->%zu). For hex conversions,
which have no signed form, cast the argument instead (%x->(unsigned),
%lx->(unsigned long), %llx->(unsigned long long)). No functional change.

Note, the fdinfo map_flags sscanf used %i into a __u32 *, which warns.
The kernel prints map_flags as hex ("map_flags:\t%#x\n" in
bpf_map_show_fdinfo(), unchanged since the field was added to fdinfo), so
switch the conversion to %x: it parses the 0x-prefixed value and expects
unsigned int *, matching the destination, so the warning is gone with no
cast.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20260624204946.2901178-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

src/btf_dump.c

@@ -1776,7 +1776,7 @@ static int btf_dump_get_bitfield_value(struct btf_dump *d,
 
 	/* Maximum supported bitfield size is 64 bits */
 	if (t->size > 8) {
-		pr_warn("unexpected bitfield size %d\n", t->size);
+		pr_warn("unexpected bitfield size %u\n", t->size);
 		return -EINVAL;
 	}
 
@@ -2251,7 +2251,7 @@ static int btf_dump_get_enum_value(struct btf_dump *d,
 		*value = is_signed ? *(__s8 *)data : *(__u8 *)data;
 		return 0;
 	default:
-		pr_warn("unexpected size %d for enum, id:[%u]\n", t->size, id);
+		pr_warn("unexpected size %u for enum, id:[%u]\n", t->size, id);
 		return -EINVAL;
 	}
 }