gyp-win-tool: Fix regression from my last change.
gyp-win-tool: Fix regression from my last change.

BUG=495204
TBR=scottmg

Review URL: https://codereview.chromium.org/1889593002 .

Phuehvk/gyp,chromium/gyp,adblockplus/gyp,msc-/gyp,chromium/gyp,Phuehvk/gyp,bnoordhuis/gyp,adblockplus/gyp,bnoordhuis/gyp,msc-/gyp,msc-/gyp,turbulenz/gyp,msc-/gyp,adblockplus/gyp,chromium/gyp,adblockplus/gyp,adblockplus/gyp,bnoordhuis/gyp,Phuehvk/gyp,chromium/gyp,turbulenz/gyp,turbulenz/gyp,bnoordhuis/gyp,chromium/gyp,Phuehvk/gyp,turbulenz/gyp,Phuehvk/gyp,msc-/gyp,turbulenz/gyp,bnoordhuis/gyp