Remove submodule directories before update.

circle.yml

@@ -7,7 +7,7 @@ dependencies:
   pre:
     - sudo apt-get update; sudo apt-get install libusb-1.0-0-dev; cd ~/; git clone https://github.com/steve-m/librtlsdr.git; cd librtlsdr; mkdir build; cd build; cmake ../; make; sudo make install; sudo ldconfig; cd ~/; mkdir gopath; cd ~/; mkdir gopath; wget https://storage.googleapis.com/golang/go1.5.1.src.tar.gz; tar -zxvf go1.5.1.src.tar.gz; cd go/src; export GOROOT_BOOTSTRAP=/usr/local/go; ./make.bash; echo $PATH; echo $GOPATH; go version; env
   override:
-    - git submodule update --init && make
+    - rm -rf dump1090 linux-mpu9150 ; git submodule update --init && make
   post:
     - rm -rf ~/.git ~/stratux