!10415 编译pytho安装环境相关说明

Merge pull request !10415 from 朱赟平/master

zh-cn/device-dev/subsystems/subsys-build-all.md

@@ -74,7 +74,9 @@ OpenHarmony编译子系统是以GN和Ninja构建为基座，对构建和配置
 - 安装方式二：apt-get和pip3 install命令安装
   ```shell
   apt-get update -y 
-  apt-get install -y apt-utils binutils bison flex bc build-essential make mtd-utils gcc-arm-linux-gnueabi u-boot-tools python3.9.2 python3-pip git zip unzip curl wget gcc g++ ruby dosfstools mtools default-jre default-jdk scons python3-distutils perl openssl libssl-dev cpio git-lfs m4 ccache zlib1g-dev tar rsync liblz4-tool genext2fs binutils-dev device-tree-compiler e2fsprogs git-core gnupg gnutls-bin gperf lib32ncurses5-dev libffi-dev zlib* libelf-dev libx11-dev libgl1-mesa-dev lib32z1-dev xsltproc x11proto-core-dev libc6-dev-i386 libxml2-dev lib32z-dev libdwarf-dev 
+  apt-get install -y  
+  # 如果是ubuntu20.04系统请直接安装python3.9，如果是ubuntu18.04请改为安装python3.8
+  apt-get install -y apt-utils binutils bison flex bc build-essential make mtd-utils gcc-arm-linux-gnueabi u-boot-tools python3.9 python3-pip git zip unzip curl wget gcc g++ ruby dosfstools mtools default-jre default-jdk scons python3-distutils perl openssl libssl-dev cpio git-lfs m4 ccache zlib1g-dev tar rsync liblz4-tool genext2fs binutils-dev device-tree-compiler e2fsprogs git-core gnupg gnutls-bin gperf lib32ncurses5-dev libffi-dev zlib* libelf-dev libx11-dev libgl1-mesa-dev lib32z1-dev xsltproc x11proto-core-dev libc6-dev-i386 libxml2-dev lib32z-dev libdwarf-dev 
   apt-get install -y grsync xxd libglib2.0-dev libpixman-1-dev kmod jfsutils reiserfsprogs xfsprogs squashfs-tools  pcmciautils quota ppp libtinfo-dev libtinfo5 libncurses5 libncurses5-dev libncursesw5 libstdc++6  gcc-arm-none-eabi vim ssh locales doxygen
   apt-get install -y libxinerama-dev libxcursor-dev libxrandr-dev libxi-dev
   # python需要安装以下模块，repo文件在上一章节约束与限制的源码获取中得到。