In the NetworkManager-1.14.4 source is a file in the m4 directory called "git-sha-record.m4"
In this file it states:
Code:
dnl GIT_SHA_RECORD($1, $2)
dnl
dnl $1: the name of the assigned variable. For example NM_GIT_SHA,
dnl NMA_GIT_SHA, LIBNL_GIT_SHA.
dnl $2: by default, a define to config.h is added. This can be
dnl suppressed by passing "no-config-h".
As to where you pass the no-config-h option I don't know, usually in the initial ./config command.