Implement wctomb(3) for ltrace.

This is an implementation in the style of the rest: char == byte.

We might want to come back and implement UTF-8, but this is enough for ltrace.

Bug: 13747066
Change-Id: Ib2b63609c9014fdef9a8491e067467c4fc5ae3cc
diff --git a/tests/Android.mk b/tests/Android.mk
index 7482ebc..e8ee687 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -82,6 +82,7 @@
     system_properties_test.cpp \
     time_test.cpp \
     unistd_test.cpp \
+    wchar_test.cpp \
 
 libBionicStandardTests_cflags := \
     $(test_cflags) \