Fix android_arm build hosted on Mac

tools/gyp/v8.gyp

Index: tools/gyp/v8.gyp
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index e0fd8ebebe9bed52acf14c519e1e54cc7ac54dd3..3a8427108b1a7bad535d7cca0f311dbcf4130b68 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -1751,11 +1751,12 @@
             ],
             'link_settings': {
               'target_conditions': [
-                ['_toolset=="host"', {
+                ['_toolset=="host" and host_os!="mac"', {
                   # Only include libdl and librt on host builds because they
                   # are included by default on Android target builds, and we
                   # don't want to re-include them here since this will change
                   # library order and break (see crbug.com/469973).
+                  # These libraries do not exist on Mac hosted builds.
                   'libraries': [
                     '-ldl',
                     '-lrt'