build: Use "relative" path for the include of all the deps

make doesn't really support relative include so we need to get the
path from the current makefile and use that ...

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

build/core-rules.mk

@@ -28,7 +28,8 @@ $(foreach core_dir, $(wildcard $(ROOT)/cores/*), $(eval include $(core_dir)/core
 
 # Resolve dependency tree for project and collect sources
 $(BUILD_TMP)/core-deps.mk: Makefile $(BUILD_TMP) $(BUILD_TMP)/deps-core-$(THIS_CORE)
-	@echo "include $(BUILD_TMP)/deps-core-*" > $@
+	@echo "SELF_DIR := \$$(dir \$$(lastword \$$(MAKEFILE_LIST)))" > $@
+	@echo "include \$$(SELF_DIR)deps-core-*" >> $@
 	@echo "CORE_ALL_DEPS := \$$(DEPS_SOLVE_TMP)" >> $@
 	@echo "CORE_ALL_RTL_SRCS := \$$(RTL_SRCS_SOLVE_TMP)" >> $@
 	@echo "CORE_ALL_SIM_SRCS := \$$(SIM_SRCS_SOLVE_TMP)" >> $@

build/project-rules.mk

@@ -37,7 +37,8 @@ $(foreach core_dir, $(wildcard $(ROOT)/cores/*), $(eval include $(core_dir)/core
 
 # Resolve dependency tree for project and collect sources
 $(BUILD_TMP)/proj-deps.mk: Makefile $(BUILD_TMP) $(addprefix $(BUILD_TMP)/deps-core-,$(PROJ_DEPS))
-	@echo "include $(BUILD_TMP)/deps-core-*" > $@
+	@echo "SELF_DIR := \$$(dir \$$(lastword \$$(MAKEFILE_LIST)))" > $@
+	@echo "include \$$(SELF_DIR)deps-core-*" >> $@
 	@echo "PROJ_ALL_DEPS := \$$(DEPS_SOLVE_TMP)" >> $@
 	@echo "PROJ_ALL_RTL_SRCS := \$$(RTL_SRCS_SOLVE_TMP)" >> $@
 	@echo "PROJ_ALL_SIM_SRCS := \$$(SIM_SRCS_SOLVE_TMP)" >> $@