make nanolib linking explicitly by each family/board

examples/build_system/make/cpu/cortex-m23.mk

@@ -0,0 +1,14 @@
+ifeq ($(TOOLCHAIN),gcc)
+  CFLAGS += \
+    -mthumb \
+    -mcpu=cortex-m23 \
+    -mfloat-abi=soft \
+
+else ifeq ($(TOOLCHAIN),iar)
+  # IAR Flags
+  CFLAGS += --cpu cortex-m23
+  ASFLAGS += --cpu cortex-m23
+endif
+
+# For freeRTOS port source
+FREERTOS_PORTABLE_SRC ?= $(FREERTOS_PORTABLE_PATH)/ARM_CM23

examples/build_system/make/toolchain/arm_gcc_rules.mk

@@ -31,10 +31,6 @@ ifdef LD_FILE_GCC
 LDFLAGS += -Wl,-T,$(TOP)/$(LD_FILE_GCC)
 endif
 
-ifneq ($(SKIP_NANOLIB), 1)
-LDFLAGS += --specs=nosys.specs --specs=nano.specs
-endif
-
 ASFLAGS += $(CFLAGS)
 
 LIBS_GCC ?= -lgcc -lm -lnosys