otautil: Factor out the utils that're private to recovery.

A number of utility functions are intended for serving recovery's own
use. Exposing them via libotautil (which is a static lib) would pass the
dependencies onto libotautil's users (e.g. recovery image, updater, host
simulator, device-specific recovery UI/updater extensions etc). This CL
finds a new home for the utils that are private to recovery.

Test: mmma bootable/recovery
Change-Id: I575e97ad099b85fe1c1c8c7c9458a5a43d4e11e1
diff --git a/Android.bp b/Android.bp
index 0eb5fd9..0759e08 100644
--- a/Android.bp
+++ b/Android.bp
@@ -72,6 +72,7 @@
         "libinstall",
         "librecovery_fastboot",
         "libminui",
+        "librecovery_utils",
         "libotautil",
 
         // external dependencies
@@ -148,7 +149,7 @@
     ],
 
     static_libs: [
-        "libotautil",
+        "librecovery_utils",
     ],
 
     init_rc: [
@@ -174,7 +175,7 @@
     ],
 
     static_libs: [
-        "libotautil",
+        "librecovery_utils",
     ],
 
     init_rc: [