GN build fixes, mostly for Mac.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 8a8ba2e00e4d60ab5d54acf0d7d78bee1c9225cb..78ddeead0e656f790abdea14a5767260b55fdfb3 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -61,12 +61,14 @@ config("compiler") {
 
   # Mac-specific compiler flags setup.
   # ----------------------------------
-  if (is_mac) {
+  if (is_mac || is_ios) {
     # These flags are shared between the C compiler and linker.
-    common_mac_flags = [
-      "-isysroot", sysroot,
-      "-mmacosx-version-min=10.6",
-    ]
+    common_mac_flags = [ "-isysroot", sysroot ]
+    if (is_mac) {
+      common_mac_flags += [ "-mmacosx-version-min=10.6" ]
+    } else {
+      cflags += [ "-mios-simulator-version-min=6.0" ]

[Nico, 2014/01/27 19:42:27]

I'm not sure if this is good enough: While the ios ninja build currently only
supports simulator builds, the xcode build supports real device builds too – so
setting the simulator flag there won't be correct.

+    }
 
     # CPU architecture.
     if (cpu_arch == "x64") {