tests/tcg: fix up test-i386-fprem.ref generation

We never shipped the reference data in the source tree because it's
quite big (64M). As a result the only option is to generate it
locally. Although we have a rule to generate the reference file we
missed the dependency and location changes, probably because it's only
run for SLOW test runs.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

tests/tcg/i386/Makefile.target

@@ -35,9 +35,9 @@ test-i386-fprem.ref: test-i386-fprem
 	$(call quiet-command, ./$< > $@,"GENREF","generating $@")
 
 run-test-i386-fprem: TIMEOUT=60
-run-test-i386-fprem: test-i386-fprem
+run-test-i386-fprem: test-i386-fprem test-i386-fprem.ref
 	$(call run-test,test-i386-fprem, $(QEMU) $<,"$< on $(TARGET_NAME)")
-	$(call diff-out,test-i386-fprem, $(I386_SRC)/$<.ref)
+	$(call diff-out,test-i386-fprem, test-i386-fprem.ref)
 else
 run-test-i386-fprem: test-i386-fprem
 	$(call skip-test, $<, "SLOW")