Make GN build work on Mac again.

build/config/BUILD.gn

Index: build/config/BUILD.gn
diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index 1dfbfe7d1130f47ecad302d0c594b5620e2d96f0..875803ef3503cea5507179ecbbb562ced88166f3 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -104,7 +104,13 @@ config("feature_flags") {
   }
   if (use_openssl) {
     defines += [ "USE_OPENSSL=1" ]
-  } else {
+    if (use_openssl_certs) {
+      defines += [ "USE_OPENSSL_CERTS=1" ]
+    }
+  } else if (use_nss_certs) {
+    # USE_NSS really means "use nss for certificate validation and storage"
+    # and not "we're linking to NSS." This should probably be renamed
+    # USE_NSS_CERTS to match OpenSSL and our build flag definitions.

[Ryan Sleevi, 2014/04/18 00:25:07]

No it should not.

OpenSSL having two flags is part of the transition away from NSS. USE_NSS is
going to go away entirely - but this flag is certainly not going to be renamed
before then. There's the distinction so that we could explicitly avoid #ifdef
churn renaming all of USE_OPENSSL / USE_NSS to something different.

     defines += [ "USE_NSS=1" ]
   }
   if (use_ozone) {