Add vita environment (#22)

* vita: initial port

* vita: implement events, enable input thread

* vita: gethostbyname

* vita: Enable audio

* vita: Fix thread crash on discoonect process

* vita: Handle cannot create thread

* vita: now use newlib's socket apis

* vita: Refactoring for moonlight-stream/moonlight-common-c

* Fix review things

https://github.com/moonlight-stream/moonlight-common-c/pull/22#pullrequestreview-2436093

- vita may not support IPv6; so add LC_ASSERT them.
- define inet_ntop to sceNetInetNtop
- guard about failure of sceKernelCreateMutex or sceKernelCreateCond
- remove meanless macros

https://github.com/moonlight-stream/moonlight-common-c/pull/22#pullrequestreview-2444677

- !*mutex to *mutex
- remove useless LC_ASSERT then change to use inet_ntop
  in vita system not defined `sockaddr_in6`, so just use `sockaddr_in` instead this.

https://github.com/moonlight-stream/moonlight-common-c/pull/22#pullrequestreview-2445642

- define sin6_addr

src/PlatformThreads.h

@@ -12,6 +12,19 @@ typedef struct _PLT_THREAD {
     HANDLE handle;
     int cancelled;
 } PLT_THREAD;
+#elif defined(__vita__)
+typedef int PLT_MUTEX;
+typedef struct _PLT_EVENT {
+    int mutex;
+    int cond;
+    int signalled;
+} PLT_EVENT;
+typedef struct _PLT_THREAD {
+    int handle;
+    int cancelled;
+    void *context;
+    int alive;
+} PLT_THREAD;
 #elif defined (LC_POSIX)
 typedef pthread_mutex_t PLT_MUTEX;
 typedef struct _PLT_EVENT {