stmhal: For non-debug compile, enable CC/LD opt to remove dead code.

Saves over 35k ROM due to elimination of unused HAL functions.  All
tests pass.

Addresses issue #702.

stmhal/Makefile

@@ -42,20 +42,21 @@ INC += -I$(CC3K_DIR)
 
 CFLAGS_CORTEX_M4 = -mthumb -mtune=cortex-m4 -mabi=aapcs-linux -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mfloat-abi=hard -fsingle-precision-constant -Wdouble-promotion
 CFLAGS = $(INC) -Wall -Werror -ansi -std=gnu99 -nostdlib $(CFLAGS_CORTEX_M4) $(COPT)
-
 CFLAGS += -Iboards/$(BOARD)
 
-#Debugging/Optimization
+LDFLAGS = -nostdlib -T stm32f405.ld -Map=$(@:.elf=.map) --cref
+LIBS =
+
+# Debugging/Optimization
 ifeq ($(DEBUG), 1)
 CFLAGS += -g -DPENDSV_DEBUG
 COPT = -O0
 else
+CFLAGS += -fdata-sections -ffunction-sections
 COPT += -Os -DNDEBUG
+LDFLAGS += --gc-sections
 endif
 
-LDFLAGS = -nostdlib -T stm32f405.ld -Map=$(@:.elf=.map) --cref
-LIBS =
-
 # uncomment this if you want libgcc
 #LIBS += $(shell $(CC) -print-libgcc-file-name)