Use String8 for UTF16 to UTF8 conversion.

This is the only actual user of libcutils' jstring.h.

Test: treehugger
Change-Id: I0444d42e5a3ca57de3bffca48aa265f267c3d4dc
diff --git a/cmds/idmap/scan.cpp b/cmds/idmap/scan.cpp
index d69dd79..847dda3 100644
--- a/cmds/idmap/scan.cpp
+++ b/cmds/idmap/scan.cpp
@@ -9,7 +9,6 @@
 #include <androidfw/ResourceTypes.h>
 #include <androidfw/StreamingZipInflater.h>
 #include <androidfw/ZipFileRO.h>
-#include <cutils/jstring.h>
 #include <cutils/properties.h>
 #include <private/android_filesystem_config.h> // for AID_SYSTEM
 #include <utils/SortedVector.h>
@@ -84,15 +83,9 @@
     }
 
     bool check_property(String16 property, String16 value) {
-        const char *prop;
-        const char *val;
-
-        prop = strndup16to8(property.string(), property.size());
         char propBuf[PROPERTY_VALUE_MAX];
-        property_get(prop, propBuf, NULL);
-        val = strndup16to8(value.string(), value.size());
-
-        return (strcmp(propBuf, val) == 0);
+        property_get(String8(property).c_str(), propBuf, NULL);
+        return String8(value) == propBuf;
     }
 
     int parse_overlay_tag(const ResXMLTree& parser, const char *target_package_name,