Simplify macro usage (PR #88 addendum)

Author: martinmoene

include/nonstd/span.hpp

@@ -180,14 +180,8 @@
 # define        span_CONFIG_CONTRACT_LEVEL_MASK  0x11
 #endif
 
-#if    defined( span_CONFIG_CONTRACT_VIOLATION_THROWS )
-# define        span_CONFIG_CONTRACT_VIOLATION_THROWS_V  span_CONFIG_CONTRACT_VIOLATION_THROWS
-#else
-# define        span_CONFIG_CONTRACT_VIOLATION_THROWS_V  0
-#endif
-
-#if    defined( span_CONFIG_CONTRACT_VIOLATION_THROWS     ) && span_CONFIG_CONTRACT_VIOLATION_THROWS && \
-       defined( span_CONFIG_CONTRACT_VIOLATION_TERMINATES ) && span_CONFIG_CONTRACT_VIOLATION_TERMINATES
+#if    span_CONFIG_CONTRACT_VIOLATION_THROWS && \
+       span_CONFIG_CONTRACT_VIOLATION_TERMINATES
 # error Please define none or one of span_CONFIG_CONTRACT_VIOLATION_THROWS and span_CONFIG_CONTRACT_VIOLATION_TERMINATES to 1, but not both.
 #endif
 
@@ -443,7 +437,7 @@ span_DISABLE_MSVC_WARNINGS( 26439 26440 26472 26473 26481 26490 )
 # define span_is_delete_access private
 #endif
 
-#if span_HAVE_NOEXCEPT && ! span_CONFIG_CONTRACT_VIOLATION_THROWS_V
+#if span_HAVE_NOEXCEPT && ! span_CONFIG_CONTRACT_VIOLATION_THROWS
 # define span_noexcept noexcept
 #else
 # define span_noexcept /*noexcept*/