Fix mac builds due to unguarded-availability error

Just bump our required base version up, as developing Android already
effectively requires 10.13, and these tools won't be distributed to
end-user developers (like fastboot/adb/aapt/etc are)

external/bison/lib/gethrxtime.c:49:9: warning: 'clock_gettime' is only available on macOS 10.12 or newer [-Wunguarded-availability]

Test: build
Change-Id: I636007e942854274ee3705a48b4f793e1cd96b71

1 files changed, 11 insertions, 0 deletions

diff --git a/Android.bp b/Android.bp
index 7f46cbe0..60fcd569 100644
--- a/Android.bp
+++ b/Android.bp
@@ -28,6 +28,17 @@ cc_defaults {
                 "darwin-lib",
                 "lib",
             ],
+
+            // This isn't being distributed to end-users, so bump up our machine
+            // requirements.
+            cflags: [
+                "-mmacosx-version-min=10.13",
+                "-UMACOSX_DEPLOYMENT_TARGET",
+                "-DMACOSX_DEPLOYMENT_TARGET=10.13",
+            ],
+            ldflags: [
+                "-mmacosx-version-min=10.13",
+            ],
         },
         linux: {
             local_include_dirs: [