N-Gage port: add changes from code reviews, overall cleanup (#5618)

* Add changes from code review by @ccawley2011, #5597, overall cleanup

* Update N-Gage README, minor cleanup and rephrasing

* Call SDL_SetMainReady() before calling SDL_main, return SDL_main instead of main

src/thread/ngage/SDL_sysmutex.cpp

@@ -20,7 +20,7 @@
 */
 #include "../../SDL_internal.h"
 
-/* An implementation of mutexes using semaphores */
+/* An implementation of mutexes using the Symbian API. */
 
 #include <e32std.h>
 
@@ -70,6 +70,22 @@ SDL_DestroyMutex(SDL_mutex * mutex)
     }
 }
 
+/* Try to lock the mutex */
+#if 0
+int
+SDL_TryLockMutex(SDL_mutex * mutex)
+{
+    if (mutex == NULL)
+    {
+        SDL_SetError("Passed a NULL mutex.");
+        return -1;
+    }
+
+    // Not yet implemented.
+    return 0;
+}
+#endif
+
 /* Lock the mutex */
 int
 SDL_LockMutex(SDL_mutex * mutex)
@@ -89,7 +105,7 @@ SDL_LockMutex(SDL_mutex * mutex)
 
 /* Unlock the mutex */
 int
-SDL_mutexV(SDL_mutex * mutex)
+SDL_UnlockMutex(SDL_mutex * mutex)
 {
     if ( mutex == NULL )
     {

src/thread/ngage/SDL_syssem.cpp

@@ -20,7 +20,7 @@
 */
 #include "../../SDL_internal.h"
 
-/* An implementation of semaphores using mutexes and condition variables */
+/* An implementation of semaphores using the Symbian API. */
 
 #include <e32std.h>
 

src/thread/ngage/SDL_systhread.cpp

@@ -128,19 +128,6 @@ SDL_SYS_DetachThread(SDL_Thread * thread)
     return;
 }
 
-/* WARNING: This function is really a last resort.
- * Threads should be signaled and then exit by themselves.
- * TerminateThread() doesn't perform stack and DLL cleanup.
- */
-void
-SDL_SYS_KillThread(SDL_Thread *thread)
-{
-    RThread rthread;
-    rthread.SetHandle(thread->handle);
-    rthread.Kill(0);
-    rthread.Close();
-}
-
 #endif /* SDL_THREAD_NGAGE */
 
 /* vim: ts=4 sw=4