Merge libmounts into libotautil.

Export its header (mounts.h) from there, and drop the dot dot dependency
from libupdater / updater.

Test: mmma bootable/recovery
Test: recovery_component_test
Change-Id: Ic26a6b9b78a34dbe1f178b138f3abaafffbec44c
diff --git a/otautil/Android.bp b/otautil/Android.bp
index 958f98b..45d119c 100644
--- a/otautil/Android.bp
+++ b/otautil/Android.bp
@@ -21,6 +21,7 @@
         "SysUtil.cpp",
         "DirUtil.cpp",
         "ThermalUtil.cpp",
+        "mounts.cpp",
         "paths.cpp",
         "rangeset.cpp",
     ],
@@ -39,4 +40,12 @@
     export_include_dirs: [
         "include",
     ],
+
+    target: {
+        darwin: {
+            exclude_srcs: [
+                "mounts.cpp",
+            ],
+        },
+    },
 }