buildInfo: Ensure we have a COMMIT_ID

[wak-google]

It's currently possible to build the current sbe without having git
installed and have the compiler complain about:

sbecmdgeneric.C:54:18: error: unable to find numeric literal operator
‘operator""x’
fwCommitId = SBE_COMMIT_ID;

This commmit makes it possible to specify a git COMMIT_ID, but fall back
to the old behavior of parsing the actual git data. It also makes sure
the process fails at this script instead of during compilation.

[wak-google]

In case this wasn't clear from the above. In some situations, like using buildroot to pull down an archive of the repo, you only get the file contents without the .git directory. We need a way to still build the SBE even without the git information. Since most tools pulling down the archive tarball needed to specify the commit id to get the tarball, it makes sense that they could pass the commit id in manually to the build process. This still falls back to parsing the git information if no commit id is specified.

[sgupta2m]

Can you please chnage

if 'COMMIT_ID' in os.environ:

•    commitStr = os.environ['COMMIT_ID'][:8]
  

to SBE_COMMIT_ID. This is too generic flag as of now.

[wkennington]

Fixed

[wak-google]

Just a heads up it looks like you merged the commit using COMMIT_ID instead of SBE_COMMIT_ID

[sgupta2m]

yeah. Thanks. bug in script which I have used for picking up the changes.