Fix the sim build

Fix the sim build

Simon pointed out that the "common/" include change in gdb broke the
sim build.  The problem was that the sim was using gdb's
create-version.sh, which changed.

This patch copies create-version.sh to the sim, so that it can
generate "version.c" in a way that works in the sim build.

Tested by rebuilding.

sim/common/ChangeLog
2019-01-26  Tom Tromey  <tom@tromey.com>

	* Make-common.in (version.c): Use sim's create-version.sh.
	* create-version.sh: New file.

sim/ppc/ChangeLog
2019-01-26  Tom Tromey  <tom@tromey.com>

	* Makefile.in (version.c): Use sim's create-version.sh.