(partially) Fix Bug#55227 Fix compiler warnings in innodb with gcc 4.6

Fix compiler warnings:
os/os0file.c: In function 'os_file_create':
os/os0file.c:1371:14: error: variable 'purpose_str' set but not used [-Werror=unused-but-set-variable]
os/os0file.c:1370:14: error: variable 'type_str' set but not used [-Werror=unused-but-set-variable]

storage/innodb_plugin/os/os0file.c

@@ -1367,8 +1367,6 @@ os_file_create(
 	int		create_flag;
 	ibool		retry;
 	const char*	mode_str	= NULL;
-	const char*	type_str	= NULL;
-	const char*	purpose_str	= NULL;
 
 try_again:
 	ut_a(name);
@@ -1388,26 +1386,9 @@ os_file_create(
 		ut_error;
 	}
 
-	if (type == OS_LOG_FILE) {
-		type_str = "LOG";
-	} else if (type == OS_DATA_FILE) {
-		type_str = "DATA";
-	} else {
-		ut_error;
-	}
+	ut_a(type == OS_LOG_FILE || type == OS_DATA_FILE);
+	ut_a(purpose == OS_FILE_AIO || purpose == OS_FILE_NORMAL);
 
-	if (purpose == OS_FILE_AIO) {
-		purpose_str = "AIO";
-	} else if (purpose == OS_FILE_NORMAL) {
-		purpose_str = "NORMAL";
-	} else {
-		ut_error;
-	}
-
-#if 0
-	fprintf(stderr, "Opening file %s, mode %s, type %s, purpose %s\n",
-		name, mode_str, type_str, purpose_str);
-#endif
 #ifdef O_SYNC
 	/* We let O_SYNC only affect log files; note that we map O_DSYNC to
 	O_SYNC because the datasync options seemed to corrupt files in 2001