Fix typo in Dockerfile

Dockerfile-ubuntu1804

 RUN apt-get update && \
     apt-get -y install g++ git sudo wget gnupg2 && \
     apt-get -y install libssl-dev build-essential && \
-    apt-get -y vim gdb strace && \
+    apt-get -y install vim gdb strace && \
     \
     echo deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main >> /etc/apt/sources.list && \
     echo deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main >> /etc/apt/sources.list && \