scons失败libmpfr.so.4: cannot open shared object file: No such file or dire

运行scons报错：

scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
Compiling src/app/ai/alg/FaceDetectIrAlg/FaceDetectAlgPostProc.cpp ...
/opt/riscv/bin/../libexec/gcc/riscv64-unknown-elf/7.2.0/cc1plus: error while loading shared libraries: libmpfr.so.4: cannot open shared object file: No such file or dire         ctory
scons: *** [build/bin/ai/app/ai/alg/FaceDetectIrAlg/FaceDetectAlgPostProc.o] Error 1
scons: building terminated because of errors.

原因路径未添加，运行如下命令即可

export LD_LIBRARY_PATH=/opt/riscv/libexec/gcc/riscv64-unknown-elf/7.2.0:$LD_LIBRARY_PATH