rtl-ssa: Include memmodel.h before tm_p.h

rtl-ssa: Include memmodel.h before tm_p.h

The RTL SSA merge broke SPARC bootstrap:

In file included from ./tm_p.h:4,
                 from /vol/gcc/src/hg/master/local/gcc/rtl-ssa.h:54,
                 from /vol/gcc/src/hg/master/local/gcc/fwprop.c:29:
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc-protos.h:45:47: error: use of enum 'memmodel' without previous declaration
 extern void sparc_emit_membar_for_model (enum memmodel, int, int);
                                               ^~~~~~~~

and similarly in rtl-ssa/functions.cc, rtl-ssa/changes.cc, and
rtl-ssa/insns.cc.

Fixed by moving the memmove.h include in rtl-ssa.h before tm_p.h.

Tested on sparc-sun-solaris2.11 and i386-pc-solaris2.11.

2020-12-17  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc:
	* rtl-ssa.h: Include memmodel.h before tm_p.h.