It's not possible to encode an OID with only one component, so some of
the NIDs do not have encodings. The logic to actually encode OIDs checks
for this (before calling der_it), but not the logic to compute the
sorted OID list.

Without this, OBJ_obj2nid, when given an empty OID, returns something
arbitrary based on the binary search implementation instead of
NID_undef.

Change-Id: Ib68bae349f66eff3d193616eb26491b6668d4b0a
Reviewed-on: https://boringssl-review.googlesource.com/7752
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

obj_mac.h is missing #include guards, so one cannot use NIDs without
pulling in the OBJ_* functions which depend on the giant OID table. Give
it #include guards, tidy up the style slightly, and also rename it to
nid.h which is a much more reasonable name.

obj_mac.h is kept as a forwarding header as, despite it being a little
screwy, some code #includes it anyway.

BUG=chromium:499653

Change-Id: Iec0b3f186c02e208ff1f7437bf27ee3a5ad004b7
Reviewed-on: https://boringssl-review.googlesource.com/7562
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

Make the commands print a short usage summary and add a README file that
explains the dependencies.

Change-Id: I0c3f0713749ecfca23afaa2b536ac70dbdd7db0a
Reviewed-on: https://boringssl-review.googlesource.com/2471
Reviewed-by: Adam Langley <agl@google.com>

OIDs with one component don't have an encoding.

PR#2556 (Bug#1)

(Imported from upstream's ff4cfc4c58 and
65e4dca40c)

Change-Id: I55b54f23e891abc2c1e0b2976531fba1f16070bb

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)