git version is missing in rom-o-matic builds

[NiKiZe]

As an example snponly.efi from rom-o-matic shows header:
iPXE 1.0.0+ -- Open Source Network Boot Firmware -- http://ipxe.org
While default build from http://boot.ipxe.org shows
iPXE 1.0.0+ (827dd) -- Open Source Network Boot Firmware -- http://ipxe.org

I think if the git command is missing when building then it becomes 1.0.0+ () -- so not sure if that is the issue or if there is something else going on.

Initially reported by tal____ on IRC

[TalAloni]

This is important for debugging purposes and should be easy to implement:
Only a single line after the call to "make" in in build.fcgi is needed, something along the lines of:
EXTRAVERSION="+ (".$revision.")"

[shodanx2]

Hello,
To reiterate, ipxe-buildweb doesn't update the boot banner to include the current version number and github build number

see discussion
ipxe/ipxe#764 (reply in thread)

This causes confusion on an already difficult and confusing topic !