google-perftools: Fix build on Linux
google-perftools: Fix build on Linux

Closes #515.

Signed-off-by: Shaun Jackman <b580dab3251a9622aba3803114310c23fdb42900@gmail.com>

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