Added a few lines at beginning, to define strnlen for Macs or else building will result in the following : "error:'strnlen' was not declared in this scope". Was able to successfully compile the latest version on a Mac after adding this.

indra/newview/llvoavatar.cpp

@@ -120,6 +120,15 @@
 
 using namespace LLVOAvatarDefines;
 
+// for macs
+#if LL_DARWIN
+size_t strnlen(const char *s, size_t n)
+{
+  const char *p = (const char *)memchr(s, 0, n);
+  return(p ? p-s : n);
+}
+#endif
+
 //-----------------------------------------------------------------------------
 // Global constants
 //-----------------------------------------------------------------------------