Add install-strip to sim/

Add install-strip to sim/

PR build/24572 notes that "make install-strip" fails.  For me, it
works in every directory except "sim", so this patch adds
install-strip targets to the Makefiles that appear there.

sim/ChangeLog
2019-12-19  Tom Tromey  <tromey@adacore.com>

	PR build/24572:
	* Makefile.in (install-strip): New target.

sim/common/ChangeLog
2019-12-19  Tom Tromey  <tromey@adacore.com>

	PR build/24572:
	* Makefile.in (install-strip): New target.

sim/igen/ChangeLog
2019-12-19  Tom Tromey  <tromey@adacore.com>

	PR build/24572:
	* Makefile.in (install-strip): New target.

sim/ppc/ChangeLog
2019-12-19  Tom Tromey  <tromey@adacore.com>

	PR build/24572:
	* Makefile.in (install-strip): New target.

sim/testsuite/ChangeLog
2019-12-19  Tom Tromey  <tromey@adacore.com>

	PR build/24572:
	* Makefile.in (install-strip): New target.

Change-Id: I76613bc5c7e7812284f33826f8a5d914477fcdc5