Fix darwin build

Disable host libmeminfo and showmap when building on darwin.

Test: m on darwin
Change-Id: Ie9342eff8d9e33c706edbb068d4ec405b480e599

libmeminfo/Android.bp

@@ -26,6 +26,12 @@ cc_defaults {
         "liblog",
         "libprocinfo",
     ],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+
+    },
 }
 
 cc_library {

libmeminfo/tools/Android.bp

@@ -67,6 +67,12 @@ cc_binary {
         "libbase",
         "libmeminfo",
     ],
+
+    target: {
+        darwin: {
+            enabled: false,
+        },
+    },
 }
 
 cc_binary {