Remove dependency on libopencm-examples and prettify Makefile a bit

Makefile

@@ -1,13 +1,13 @@
 OPENCM3_DIR := libopencm3
 
-EXAMPLE_DIR = /home/ledoian/Development/STM32/libopencm3-examples/libopencm3-examples/examples/stm32/f1/stm32vl-discovery
-#EXAMPLE_DIR = /home/ledoian/libopencm3-examples/libopencm3-examples/examples/stm32/f1/stm32vl-discovery
+# NB: Not exhaustive, some still hardcoded.
+CPU_FLAGS := -mthumb -mcpu=cortex-m3 -msoft-float -mfix-cortex-m3-ldrd
 
 %.o: %.c
-	arm-none-eabi-gcc -Os -g -Wextra -fno-common -ffunction-sections -fdata-sections -MD -Wall -Wundef -I $(OPENCM3_DIR)/include -D STM32F1 -mthumb -mcpu=cortex-m3 -msoft-float -mfix-cortex-m3-ldrd -c $*.c -o $*.o
+	arm-none-eabi-gcc -Os -g -Wextra -fno-common -ffunction-sections -fdata-sections -Wall -Wundef -I $(OPENCM3_DIR)/include -D STM32F1 ${CPU_FLAGS} -c $*.c -o $*.o
 
 %.elf: %.o
-	arm-none-eabi-gcc --static -nostartfiles -L $(OPENCM3_DIR)/lib -T $(EXAMPLE_DIR)/stm32vl-discovery.ld -Wl,-Map=$*.map -Wl,--gc-sections -mthumb -mcpu=cortex-m3 -msoft-float -mfix-cortex-m3-ldrd $*.o -l opencm3_stm32f1 -Wl,--start-group -lc -lgcc -lnosys -Wl,--end-group -o $*.elf
+	arm-none-eabi-gcc --static -nostartfiles -L $(OPENCM3_DIR)/lib -T $(OPENCM3_DIR)/lib/stm32/f1/stm32f100xb.ld -Wl,-Map=$*.map -Wl,--gc-sections ${CPU_FLAGS} $*.o -l opencm3_stm32f1 -Wl,--start-group -lc -lgcc -lnosys -Wl,--end-group -o $*.elf
 
 %.bin: %.elf
 	arm-none-eabi-objcopy -Obinary $*.elf $*.bin