Implement <iconv.h>.

Bug: http://b/32978596
Test: ran tests
Change-Id: I56b6ae3d9c5a3a56d2b4afba33fb8f9e964bf7b9
diff --git a/tests/Android.bp b/tests/Android.bp
index ea3f39f..b5f8dc8 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -70,6 +70,7 @@
         "getauxval_test.cpp",
         "getcwd_test.cpp",
         "grp_pwd_test.cpp",
+        "iconv_test.cpp",
         "ifaddrs_test.cpp",
         "inttypes_test.cpp",
         "langinfo_test.cpp",