Disable libraries using eventfd on darwin hosts.

The eventfd API is not supported on darwin/MacOS. Since these
libraries are not meant for host use we will simply not build them for
those platforms. The libraries disabled are libdt_fd_forward and
libadbconnection. Both of these libraries are used for debugging
support on device only so it should not be any real issue.

Test: None
Change-Id: Ia1b1efc50a0bd9427640edec322db5ebd37d92a2
diff --git a/adbconnection/Android.bp b/adbconnection/Android.bp
index b2f82dd..441b706 100644
--- a/adbconnection/Android.bp
+++ b/adbconnection/Android.bp
@@ -37,6 +37,9 @@
         },
         host: {
         },
+        darwin: {
+            enabled: false,
+        },
     },
     header_libs: [
         "libnativehelper_header_only",
diff --git a/dt_fd_forward/Android.bp b/dt_fd_forward/Android.bp
index 84faa08..1ba2323 100644
--- a/dt_fd_forward/Android.bp
+++ b/dt_fd_forward/Android.bp
@@ -34,6 +34,9 @@
         },
         host: {
         },
+        darwin: {
+            enabled: false,
+        },
     },
     header_libs: [
         "javavm_headers",