MANIFEST: Add lib/include/bpf

The tarball wasn't working without this file:

  [ 32%] Building C object CMakeFiles/dwarves.dir/btf_encoder.c.o
  /tmp/dwarves-1.22/btf_encoder.c:18:10: fatal error: bpf/btf.h: No such file or directory
   #include <bpf/btf.h>
            ^~~~~~~~~~~
  compilation terminated.

Cc: Luca Boccassi <[email protected]>
Fixes: 82756ea ("libbpf: Fixup patch to allow to use packaged version")
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

MANIFEST

@@ -68,3 +68,4 @@ libctf.c
 libctf.h
 regtest
 lib/bpf/
+lib/include/bpf