[Buildroot] buildroot not support c++ compliing

[olyvine.chen at logiways.com.cn]

Dear all,
        
  I now try to add package libmusicbrainz to buildroot, but many errors
happen, such as the following:

*************************************************************************

buildroot/output/build/libmusicbrainz-3.0.2/src/artist.cpp:23:18: error:
string: No such file or directory

*************************************************************************
  it seems indicate that no c++ library available, then how to enable c
++ compiling for buildroot? 
        
  I enabled glibc via:
  Toolchain => Toolchain type (External toolchain) => External toolchain
C library (glibc)
        
Kindest regards!
Olyvine