tests/tcg/multiarch: add hello world system test

This is not really i386 only, we can have the same test for all
architectures supporting system tests.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>

tests/tcg/i386/Makefile.softmmu-target

@@ -27,7 +27,7 @@ CFLAGS+=-m32
 LINK_SCRIPT=$(I386_SYSTEM_SRC)/kernel.ld
 LDFLAGS=-Wl,-T$(LINK_SCRIPT) -Wl,-melf_i386
 # FIXME: move to common once x86_64 is bootstrapped
-TESTS+=$(X86_TESTS)
+TESTS+=$(X86_TESTS) $(MULTIARCH_TESTS)
 endif
 CFLAGS+=-nostdlib -ggdb -O0 $(MINILIB_INC)
 LDFLAGS+=-static -nostdlib $(CRT_OBJS) $(MINILIB_OBJS) -lgcc