libxl/ACPI: add missing build dependency

Just like all other object files - wherever *.o is mentioned, *.opic
also needs mentioning to yield consistent behavior. Otherwise make may
decide to (re)build the object before recursion into $(ACPI_PATH)/ (to
update $(DSDT_FILES-y) and ssdt_*.h) was actually finished.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>

tools/libs/light/Makefile

@@ -32,7 +32,7 @@ ACPI_PATH  = $(XEN_ROOT)/tools/libacpi
 DSDT_FILES-$(CONFIG_X86) = dsdt_pvh.c
 ACPI_OBJS  = $(patsubst %.c,%.o,$(DSDT_FILES-y)) build.o static_tables.o
 ACPI_PIC_OBJS = $(patsubst %.o,%.opic,$(ACPI_OBJS))
-$(DSDT_FILES-y) build.o: acpi
+$(DSDT_FILES-y) build.o build.opic: acpi
 vpath build.c $(ACPI_PATH)/
 vpath static_tables.c $(ACPI_PATH)/