Unbreak naclports build.
Unbreak naclports build.

My previous CL seems to have broken naclports because NACL_CPP_LIB isn't
defined. Export it so it is defined.

Previous CL: https://codereview.chromium.org/92733002/

R=sbc@chromium.org
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3623

Review URL: https://codereview.chromium.org/99883004

git-svn-id: 84b3587ce119b778414dcb50e18b7479aacf4f1d@1002 7dad1e8b-422e-d2af-fbf5-8013b78bd812

Schibum/naclports,yeyus/naclports,binji/naclports,kuscsik/naclports,yeyus/naclports,clchiou/naclports,binji/naclports,kosyak/naclports_samsung-smart-tv,yeyus/naclports,kosyak/naclports_samsung-smart-tv,adlr/naclports,binji/naclports,dtkav/naclports,binji/naclports,yeyus/naclports,yeyus/naclports,kuscsik/naclports,adlr/naclports,kuscsik/naclports,binji/naclports,adlr/naclports,clchiou/naclports,clchiou/naclports,kuscsik/naclports,dtkav/naclports,dtkav/naclports,adlr/naclports,Schibum/naclports,Schibum/naclports,kosyak/naclports_samsung-smart-tv,adlr/naclports,yeyus/naclports,Schibum/naclports,dtkav/naclports,kosyak/naclports_samsung-smart-tv,clchiou/naclports,clchiou/naclports,kosyak/naclports_samsung-smart-tv,Schibum/naclports,kuscsik/naclports,dtkav/naclports,Schibum/naclports