mips64el平台编译cmake时提示 The C++ compiler does not support C++11

./bootstrap
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CMake 3.12.4, Copyright 2000-2018 Kitware, Inc. and Contributors
Found GNU toolchain
C compiler on this system is: gcc       
C++ compiler on this system is: g++          
Makefile processor on this system is: gmake
g++ has setenv
g++ has unsetenv
g++ does not have environ in stdlib.h
g++ has stl wstring
g++ has <ext/stdio_filebuf.h>
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gmake: “cmake”是最新的。
loading initial cache file /home/CompileSrcGit/cmake-3.12.4/Bootstrap.cmk/InitialCacheFlags.cmake
CMake Error at CMakeLists.txt:92 (message):
  The C++ compiler does not support C++11 (e.g.  std::unique_ptr).

-- Configuring incomplete, errors occurred!
See also "/home/CompileSrcGit/cmake-3.12.4/CMakeFiles/CMakeOutput.log".
See also "/home/CompileSrcGit/cmake-3.12.4/CMakeFiles/CMakeError.log".
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Error when bootstrapping CMake:
Problem while running initial CMake
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解决过程：

先查询了gcc版本，这里因为我事先编译安装了gcc源码。

[root@localhost cmake-3.12.4]# gcc --version
gcc (GCC) 8.2.0
Copyright © 2018 Free Software Foundation, Inc.
本程序是自由软件；请参看源代码的版权声明。本软件没有任何担保；
包括没有适销性和某一专用目的下的适用性担保。

以上表明gcc没有问题，其实gcc4.8以上即可。

执行以下来解决。

[root@localhost cmake-3.12.4]# export CXXFLAGS="-std=c++11"

[root@localhost cmake-3.12.4]# ./bootstrap