Added thread-safe build+size reporting to CI

.travis.yml

@@ -208,12 +208,12 @@ jobs:
     script:
       - make test TFLAGS+="-k --valgrind"
 
-  # test compilation in read-only mode
+  # test compilation in thread-safe mode
   - stage: test
     env:
-      - NAME=littlefs-readonly
+      - NAME=littlefs-threadsafe
       - CC="arm-linux-gnueabi-gcc --static -mthumb"
-      - CFLAGS="-Werror -DLFS_READONLY"
+      - CFLAGS="-Werror -DLFS_THREADSAFE"
     if: branch !~ -prefix$
     install:
       - *install-common