linker: Only link to debuggerd on Android

Don't link to it when building with bionic for the host.

Also add libasync_safe, which is used by linker_globals.h even when
debuggerd isn't used.

Bug: 31559095
Test: mma
Test: Attempt to build host bionic
Change-Id: I374e2c2c288133875da82de780b27917ca524240

linker/Android.bp

@@ -136,7 +136,7 @@ cc_binary {
         "libbase",
         "libz",
 
-        "libdebuggerd_handler_fallback",
+        "libasync_safe",
 
         "liblog",
         "libc++_static",
@@ -156,7 +156,7 @@ cc_binary {
     },
     target: {
         android: {
-            static_libs: ["libdebuggerd_client"],
+            static_libs: ["libdebuggerd_handler_fallback"],
         },
         android64: {
             cflags: ["-DTARGET_IS_64_BIT"],