iiod: Ensure that we always send 7 chars for the GIT tag
iiod: Ensure that we always send 7 chars for the GIT tag

If libiio is built from a tarball instead of from the GIT tree, the GIT
tag will correspond to a tag, e.g. "v0.2". This commit ensures that we
still send 7 characters, as expected by the network backend of libiio.

Signed-off-by: Paul Cercueil <73d292422978d45c9eeef455bb1b24a0db453722@analog.com>

analogdevicesinc/libiio,sensarliar/libiio,Sunderfield/libiio,analogdevicesinc/libiio,gburca/libiio,sensarliar/libiio,analogdevicesinc/libiio,analogdevicesinc/libiio,gburca/libiio,sensarliar/libiio,Sunderfield/libiio,Sunderfield/libiio,gburca/libiio