FT-599 switched from _SVID_SOURCE to _DEFAULT_SOURCE

Newer libc doesn't like _SVID_SOURCE:
https://sourceware.org/ml/libc-alpha/2013-12/msg00652.html

cmake_modules/TokuSetupCompiler.cmake

@@ -17,7 +17,7 @@ add_c_defines(
 if (NOT CMAKE_SYSTEM_NAME STREQUAL FreeBSD)
   ## on FreeBSD these types of macros actually remove functionality
   add_c_defines(
-    _SVID_SOURCE
+    _DEFAULT_SOURCE
     _XOPEN_SOURCE=600
     )
 endif ()