Change macro to MODULE_MISSING_EXPORTS for clarity

This is a bit more clear than MODULE_FUNCTION_NOT_FOUND.

libobs/obs-defs.h

@@ -29,7 +29,7 @@
 #define MODULE_SUCCESS             0
 #define MODULE_ERROR              -1
 #define MODULE_FILE_NOT_FOUND     -2
-#define MODULE_FUNCTION_NOT_FOUND -3
+#define MODULE_MISSING_EXPORTS    -3
 #define MODULE_INCOMPATIBLE_VER   -4
 
 #define OBS_OUTPUT_SUCCESS         0

libobs/obs-module.c

@@ -30,7 +30,7 @@ static inline int req_func_not_found(const char *name, const char *path)
 	blog(LOG_ERROR, "Required module function '%s' in module '%s' not "
 	                "found, loading of module failed",
 	                name, path);
-	return MODULE_FUNCTION_NOT_FOUND;
+	return MODULE_MISSING_EXPORTS;
 }
 
 #define LOAD_REQ_SIZE_FUNC(func, module, path)         \