Configure: set NGX_KQUEUE_UDATA_T at compile time.

The NGX_KQUEUE_UDATA_T macro is used to compensate the incompatible
kqueue() API in NetBSD, it doesn't really belong to feature tests.

The change limits the macro visibility to the kqueue event module.
Moving from autotests also simplifies testing a particular NetBSD
version as seen in a subsequent change.

auto/unix

@@ -129,26 +129,6 @@ if test -z "$NGX_KQUEUE_CHECKED"; then
 fi
 
 
-if [ "$NGX_SYSTEM" = "NetBSD" ]; then
-
-    # NetBSD 2.0 incompatibly defines kevent.udata as "intptr_t"
-
-    cat << END >> $NGX_AUTO_CONFIG_H
-
-#define NGX_KQUEUE_UDATA_T
-
-END
-
-else
-    cat << END >> $NGX_AUTO_CONFIG_H
-
-#define NGX_KQUEUE_UDATA_T  (void *)
-
-END
-
-fi
-
-
 ngx_feature="crypt()"
 ngx_feature_name="NGX_HAVE_CRYPT"
 ngx_feature_run=no

src/event/modules/ngx_kqueue_module.c

@@ -10,6 +10,15 @@
 #include <ngx_event.h>
 
 
+/* NetBSD 2.0 incompatibly defines kevent.udata as "intptr_t" */
+
+#if (__NetBSD__)
+#define NGX_KQUEUE_UDATA_T
+#else
+#define NGX_KQUEUE_UDATA_T  (void *)
+#endif
+
+
 typedef struct {
     ngx_uint_t  changes;
     ngx_uint_t  events;