Fix Any::TypeMismatch unit test

The expected error message relied too much on demangling of std::string.

On Android, it shows as std::__1::basic_string<...>. So just use a
rough regex to match the error message but do not use it verbatim.

Change-Id: I2c6c7810bf028118cf2ebeb7bd04f47d1da835e5
diff --git a/brillo/ b/brillo/
index 506559b..2af8845 100644
--- a/brillo/
+++ b/brillo/
@@ -245,7 +245,7 @@
   val = std::string("123");
-               "Unable to convert value of type 'std::string' to integer");
+               "Unable to convert value of type 'std::.*' to integer");
   Any empty;
   EXPECT_DEATH(empty.GetAsInteger(), "Must not be called on an empty Any");