build: explicitly define dependency files

Groundwork for distcc support in Android build system,
see distcc FAQ for details on why -MF is needed:
http://distcc.googlecode.com/svn/trunk/doc/web/faq.html

core/definitions.mk

@@ -890,7 +890,7 @@ $(hide) $(PRIVATE_CXX) \
 	$(PRIVATE_CFLAGS) \
 	$(PRIVATE_CPPFLAGS) \
 	$(PRIVATE_DEBUG_CFLAGS) \
-	-MD -o $@ $<
+	-MD -MF $(patsubst %.o,%.d,$@) -o $@ $<
 $(transform-d-to-p)
 endef
 
@@ -917,7 +917,7 @@ $(hide) $(PRIVATE_CC) \
 	$(PRIVATE_CFLAGS) \
 	$(1) \
 	$(PRIVATE_DEBUG_CFLAGS) \
-	-MD -o $@ $<
+	-MD -MF $(patsubst %.o,%.d,$@) -o $@ $<
 endef
 
 define transform-c-to-o-no-deps
@@ -978,7 +978,7 @@ $(hide) $(PRIVATE_CXX) \
 	$(PRIVATE_CFLAGS) \
 	$(PRIVATE_CPPFLAGS) \
 	$(PRIVATE_DEBUG_CFLAGS) \
-	-MD -o $@ $<
+	-MD -MF $(patsubst %.o,%.d,$@) -o $@ $<
 $(transform-d-to-p)
 endef
 
@@ -1004,7 +1004,7 @@ $(hide) $(PRIVATE_CC) \
 	$(PRIVATE_CFLAGS) \
 	$(1) \
 	$(PRIVATE_DEBUG_CFLAGS) \
-	-MD -o $@ $<
+	-MD -MF $(patsubst %.o,%.d,$@) -o $@ $<
 endef
 
 define transform-host-c-to-o-no-deps