Only #define va_copy if it isn't #defined yet

git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@6367 4a71c877-e1ca-e34f-864e-861f7616d084

lib/framework/wzglobal.h

@@ -278,6 +278,7 @@
 #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
 # define WZ_C99
 #else
+# if !defined(va_copy)
 /**
  * Implements the interface of the C99 macro va_copy such that we can use it on
  * non-C99 systems as well.
@@ -287,6 +288,7 @@
  * it might not always work.
  */
 #  define va_copy(dest, src) (void)((dest) = (src))
+# endif
 #endif /* WZ_Cxx */