Add circle job to monitor bootloader size (ARMmbed#49)

builds the bootloader and generate a size graph
using https://github.com/ARMmbed/mbed-os-linker-report

Author: LiyouZhou

circle.yml

@@ -0,0 +1,24 @@
+dependencies:
+  pre:
+    - sudo apt-get remove binutils-arm-none-eabi gcc-arm-none-eabi -y
+    - sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa -y
+    - sudo apt-get update -y
+    - sudo apt-get install gcc-arm-embedded -y
+    - pip install mbed-cli
+    - mkdir -p ~/cli-cache
+    - mbed config --global cache ~/cli-cache
+    - cd ../ && git clone https://github.com/ARMmbed/mbed-os-linker-report.git --depth 1
+  cache_directories:
+    - "~/cli-cache"
+
+test:
+  override:
+    - mbed deploy --protocol ssh
+    - mbed compile -m K64F -t GCC_ARM --profile=../mbed-os-linker-report/compiler_profiles/release.json
+    - echo $(stat --printf="%s" BUILD/K64F/GCC_ARM/mbed-bootloader-internal.bin) | tee BINSIZE # current build size 
+  post:
+    - python ../mbed-os-linker-report/elfsize.py -i BUILD/K64F/GCC_ARM/mbed-bootloader-internal.elf
+    - mkdir -p $CIRCLE_ARTIFACTS/mbed-os-linker-report/
+    - cp -r ../mbed-os-linker-report/html $CIRCLE_ARTIFACTS/mbed-os-linker-report/
+    - cp ../mbed-os-linker-report/index.html $CIRCLE_ARTIFACTS/mbed-os-linker-report/
+    - echo $(cat BINSIZE) > $CIRCLE_ARTIFACTS/bin_size_$(cat BINSIZE)