Use inlined demangler on FreeBSD

FreeBSD includes the elftoolchain project's demangler in the base system.
It does not handle some unusual mangled names, so use the inlined
libcxxabi one.

llvm-svn: 193776
diff --git a/lldb/source/Core/Mangled.cpp b/lldb/source/Core/Mangled.cpp
index 8e2479d..da27d2d 100644
--- a/lldb/source/Core/Mangled.cpp
+++ b/lldb/source/Core/Mangled.cpp
@@ -10,7 +10,7 @@
 
 // FreeBSD9-STABLE requires this to know about size_t in cxxabi.h
 #include <cstddef>
-#ifdef _MSC_VER
+#if defined(_MSC_VER) || defined (__FreeBSD__)
 #define LLDB_USE_BUILTIN_DEMANGLER
 #else
 #include <cxxabi.h>