mkdir -p, clear cmake for libfuzzer build

docker/Dockerfile

@@ -65,8 +65,9 @@ RUN git clone https://github.com/SoftSec-KAIST/Eclipser \
 
 # Install DeepState using a few different compilers for AFL/libFuzzer/Eclipser+normal
 RUN cd deepstate \
-    && mkdir build \
+    && mkdir -p build \
     && cd build \
+    && rm -rf CMakeFiles CMakeCache.txt \
     && CXX=clang++ CC=clang BUILD_LIBFUZZER=TRUE cmake ../ \
     && sudo make install \
     && rm -rf CMakeFiles CMakeCache.txt \