Wasm: Add core configuration data structure.

This is required to actually _build_ the Wasm language module.

The nxt_wasm_app_conf_t structure consists of the modules name, e.g
wasm, then the three required function handlers followed by the five
optional function handlers.

See the next commit for details of these function handlers.

We also need to include the u.wasm union entry that provides access to
the above structure.

The bulk of the configuration infrastructure will be added in a
subsequent commit.

Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

src/nxt_application.h

@@ -87,6 +87,21 @@ typedef struct {
 } nxt_java_app_conf_t;
 
 
+typedef struct {
+    const char        *module;
+
+    const char        *request_handler;
+    const char        *malloc_handler;
+    const char        *free_handler;
+
+    const char        *module_init_handler;
+    const char        *module_end_handler;
+    const char        *request_init_handler;
+    const char        *request_end_handler;
+    const char        *response_end_handler;
+} nxt_wasm_app_conf_t;
+
+
 struct nxt_common_app_conf_s {
     nxt_str_t                  name;
     nxt_str_t                  type;
@@ -115,6 +130,7 @@ struct nxt_common_app_conf_s {
         nxt_perl_app_conf_t      perl;
         nxt_ruby_app_conf_t      ruby;
         nxt_java_app_conf_t      java;
+        nxt_wasm_app_conf_t      wasm;
     } u;
 
     nxt_conf_value_t           *self;