Fixed some compiler warnings that Visual Studio reported.

include/SDL_thread.h

@@ -49,7 +49,7 @@ typedef struct SDL_Thread SDL_Thread;
 typedef unsigned long SDL_threadID;
 
 /* Thread local storage ID, 0 is the invalid ID */
-typedef unsigned SDL_TLSID;
+typedef unsigned int SDL_TLSID;
 
 /* The SDL thread priority
  *

src/stdlib/SDL_string.c

@@ -1350,7 +1350,7 @@ SDL_PrintUnsignedLongLong(char *text, size_t maxlen, SDL_FormatInfo *info, Uint6
 static size_t
 SDL_PrintFloat(char *text, size_t maxlen, SDL_FormatInfo *info, double arg)
 {
-    int i, width;
+    int width;
     size_t len;
     size_t left = maxlen;
     char *textstart = text;

src/thread/SDL_thread.c

@@ -57,8 +57,8 @@ SDL_TLSSet(SDL_TLSID id, const void *value, void (*destructor)(void *))
     }
 
     storage = SDL_SYS_GetTLSData();
-    if (!storage || id > storage->limit) {
-        int i, oldlimit, newlimit;
+    if (!storage || (id > storage->limit)) {
+        unsigned int i, oldlimit, newlimit;
 
         oldlimit = storage ? storage->limit : 0;
         newlimit = (id + TLS_ALLOC_CHUNKSIZE);

src/thread/SDL_thread_c.h

@@ -58,7 +58,7 @@ extern void SDL_RunThread(void *data);
 
 /* This is the system-independent thread local storage structure */
 typedef struct {
-    int limit;
+    unsigned int limit;
     struct {
         void *data;
         void (*destructor)(void*);

src/video/SDL_surface.c

@@ -178,7 +178,7 @@ SDL_SetColorKey(SDL_Surface * surface, int flag, Uint32 key)
         return SDL_InvalidParamError("surface");
     }
 
-    if (surface->format->palette && key >= surface->format->palette->ncolors) {
+    if (surface->format->palette && key >= ((Uint32) surface->format->palette->ncolors)) {
         return SDL_InvalidParamError("key");
     }