Print git version at startup

[ricarkol]

Print the git version somewhere in the middle of this.

            |      ___|
  __|  _ \  |  _ \ __ \
\__ \ (   | | (   |  ) |
____/\___/ _|\___/____/
Solo5: Memory map: 1024 MB addressable:
Solo5:     unused @ (0x0 - 0xfffff)
Solo5:       text @ (0x100000 - 0x2ed863)
Solo5:     rodata @ (0x2ed864 - 0x335777)
Solo5:       data @ (0x335778 - 0x404de7)
Solo5:       heap >= 0x405000 < stack < 0x40000000
rump kernel bare metal bootstrap

Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 7.99.34 (RUMP-ROAST)
total memory = 509 MB
timecounter: Timecounters tick every 10.000 msec
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
cpu0 at thinair0: rump virtual cpu
root file system type: rumpfs
kern.module.path=/stand/amd64/7.99.34/modules
mainbus0 (root)
timecounter: Timecounter "bmktc" frequency 1000000000 Hz quality 100
rumprun: could not find start of json.  no config?
mounted tmpfs on /tmp

=== calling "rumprun" main() ===