doctor: Check for LD_* variables for Linuxbrew
doctor: Check for LD_* variables for Linuxbrew

Setting LD_* vars can break dynamic linking.

DoomHammer/linuxbrew,reelsense/linuxbrew,DoomHammer/linuxbrew,gnubila-france/linuxbrew,Angeldude/linuxbrew,reelsense/linuxbrew,SuperNEMO-DBD/cadfaelbrew,saketkc/linuxbrew,saketkc/linuxbrew,saketkc/linuxbrew,sjackman/linuxbrew,Homebrew/linuxbrew,saketkc/linuxbrew,Linuxbrew/linuxbrew,Angeldude/linuxbrew,sjackman/linuxbrew,Linuxbrew/linuxbrew,Angeldude/linuxbrew,DoomHammer/linuxbrew,drbenmorgan/linuxbrew,SuperNEMO-DBD/cadfaelbrew,Homebrew/linuxbrew,Homebrew/linuxbrew,Linuxbrew/linuxbrew,DoomHammer/linuxbrew,gnubila-france/linuxbrew,gnubila-france/linuxbrew,reelsense/linuxbrew,Angeldude/linuxbrew,Linuxbrew/linuxbrew,SuperNEMO-DBD/cadfaelbrew,drbenmorgan/linuxbrew,gnubila-france/linuxbrew,sjackman/linuxbrew,drbenmorgan/linuxbrew,sjackman/linuxbrew,drbenmorgan/linuxbrew,reelsense/linuxbrew,Homebrew/linuxbrew,SuperNEMO-DBD/cadfaelbrew