x86: fix dependencies of emulator test

Rather than mentioning the (linked) directory, mention the files thus
making sure things get rebuild as needed when the core emulator files
change.

Also enable debug info generation unconditionally, as this is testing
stuff only anyway.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/tools/tests/x86_emulator/Makefile
+++ b/tools/tests/x86_emulator/Makefile
@@ -37,14 +37,13 @@ clean:
 .PHONY: install
 install:
 
-.PHONY: x86_emulate
-x86_emulate:
+x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h:
 	[ -L x86_emulate ] || ln -sf $(XEN_ROOT)/xen/arch/x86/x86_emulate .
 
 HOSTCFLAGS += $(CFLAGS_xeninclude)
 
-x86_emulate.o: x86_emulate.c x86_emulate
-	$(HOSTCC) $(HOSTCFLAGS) -c -o $@ $<
+x86_emulate.o: x86_emulate.c x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h
+	$(HOSTCC) $(HOSTCFLAGS) -c -g -o $@ $<
 
-test_x86_emulator.o: test_x86_emulator.c blowfish.h x86_emulate
-	$(HOSTCC) $(HOSTCFLAGS) -c -o $@ $<
+test_x86_emulator.o: test_x86_emulator.c blowfish.h x86_emulate/x86_emulate.h
+	$(HOSTCC) $(HOSTCFLAGS) -c -g -o $@ $<