Enforce dropping the isset macro from sys/param.h

builtin_functions.h can't compile on
platforms where sys/param.h gets included later
in the #include stack than builtin_functions.h

By explicitly including it here and clearing the
macro, we ensure it doesn't get reset.

src/runtime/base/builtin_functions.h

@@ -32,7 +32,15 @@
 #include <runtime/base/util/request_local.h>
 #include <util/case_insensitive.h>
 
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(__FreeBSD__)
+/**
+ * We don't actually use param.h in this file,
+ * but other files which use us do, and we want
+ * to enforce clearing of the isset macro from
+ * that header by handling the header now
+ * and wiping it out.
+ */
+# include <sys/param.h>
 # ifdef isset
 #  undef isset
 # endif