Remove extra blank line

Author: gmlueck

adoc/chapters/programming_interface.adoc

@@ -14,7 +14,6 @@ document, not pertaining to any particular <<backend>>.
 All functions defined in this specification are thread-safe, unless otherwise
 specified.
 
-
 The underlying types for all enumerations defined in this specification are
 implementation-defined.
 In addition, all enumerators within an enumeration have some