MAINTAINERS: record lib/buildid.c as owned by BPF subsystem

Build ID fetching code originated from ([0]), and is still both owned
and heavily relied upon by BPF subsystem.

Fix the original omission in [0] to record this fact in MAINTAINERS.

  [0] bd7525d ("bpf: Move stack_map_get_build_id into lib")

Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Song Liu <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: anakryiko

MAINTAINERS

@@ -4098,6 +4098,7 @@ F:	include/uapi/linux/btf*
 F:	include/uapi/linux/filter.h
 F:	kernel/bpf/
 F:	kernel/trace/bpf_trace.c
+F:	lib/buildid.c
 F:	lib/test_bpf.c
 F:	net/bpf/
 F:	net/core/filter.c
@@ -4218,6 +4219,7 @@ L:	[email protected]
 S:	Maintained
 F:	kernel/bpf/stackmap.c
 F:	kernel/trace/bpf_trace.c
+F:	lib/buildid.c
 
 BROADCOM ASP 2.0 ETHERNET DRIVER
 M:	Justin Chen <[email protected]>