cmake: fix regression with linux make builds

Closes https://github.com/espressif/esp-idf/issues/2839

make/ldgen.mk

@@ -3,19 +3,23 @@
 LDGEN_SECTIONS_INFO_FILES = $(foreach lib, $(COMPONENT_LIBRARIES), $(BUILD_DIR_BASE)/$(lib)/lib$(lib).a.sections_info)
 LDGEN_FRAGMENT_FILES = $(COMPONENT_LDFRAGMENTS)
 
+ON_WINDOWS:=n
+
+ifdef OS
+	ifeq ($(OS),Windows_NT)
+		ON_WINDOWS:=y
+	endif
+endif
+
 # Target to generate linker script generator from fragments presented by each of
 # the components
+ifeq ($(ON_WINDOWS),y)
 define ldgen_process_template
 $(BUILD_DIR_BASE)/ldgen.section_infos: $(LDGEN_SECTIONS_INFO_FILES) $(IDF_PATH)/make/ldgen.mk
-ifeq ($(OS), Windows_NT)
 	printf "$(foreach info,$(LDGEN_SECTIONS_INFO_FILES),$(subst \,/,$(shell cygpath -w $(info)))\n)" > $(BUILD_DIR_BASE)/ldgen.section_infos
-else
-	printf "$(foreach info,$(LDGEN_SECTIONS_INFO_FILES),$(info)\n)" > $(BUILD_DIR_BASE)/ldgen.section_infos
-endif
 
 $(2): $(1) $(LDGEN_FRAGMENT_FILES) $(SDKCONFIG) $(BUILD_DIR_BASE)/ldgen.section_infos
 	@echo 'Generating $(notdir $(2))'
-ifeq ($(OS), Windows_NT)
 	$(PYTHON) $(IDF_PATH)/tools/ldgen/ldgen.py \
 		--input         $(1) \
 		--config        $(SDKCONFIG) \
@@ -26,7 +30,14 @@ ifeq ($(OS), Windows_NT)
 		--env           "COMPONENT_KCONFIGS=$(foreach k, $(COMPONENT_KCONFIGS), $(shell cygpath -w $(k)))" \
 		--env           "COMPONENT_KCONFIGS_PROJBUILD=$(foreach k, $(COMPONENT_KCONFIGS_PROJBUILD), $(shell cygpath -w $(k)))" \
 		--env           "IDF_CMAKE=n"
-else
+endef
+else # ON_WINDOWS
+define ldgen_process_template
+$(BUILD_DIR_BASE)/ldgen.section_infos: $(LDGEN_SECTIONS_INFO_FILES) $(IDF_PATH)/make/ldgen.mk
+	printf "$(foreach info,$(LDGEN_SECTIONS_INFO_FILES),$(info)\n)" > $(BUILD_DIR_BASE)/ldgen.section_infos
+
+$(2): $(1) $(LDGEN_FRAGMENT_FILES) $(SDKCONFIG) $(BUILD_DIR_BASE)/ldgen.section_infos
+	@echo 'Generating $(notdir $(2))'
 	$(PYTHON) $(IDF_PATH)/tools/ldgen/ldgen.py \
 		--input         $(1) \
 		--config        $(SDKCONFIG) \
@@ -37,8 +48,8 @@ else
 		--env           "COMPONENT_KCONFIGS=$(COMPONENT_KCONFIGS)" \
 		--env           "COMPONENT_KCONFIGS_PROJBUILD=$(COMPONENT_KCONFIGS_PROJBUILD)" \
 		--env           "IDF_CMAKE=n"
-endif
 endef
+endif # ON_WINDOWS
 
 define ldgen_create_commands
 $(foreach lib, $(COMPONENT_LIBRARIES), \