GN: fix mac build again
Hoping to land these using the other GN bots as trybots.
Don't know what magic was letting us get to webp's headers yesterday on Linux. Might have been using /usr/include's ?
The other change is the difference between some setups using #define SK_BUILD_FOR_MAC and others #define SK_BUILD_FOR_MAC 1. We want either to mean "we're Mac".
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2190713004
Review-Url: https://codereview.chromium.org/2190713004
2 files changed