print: use stdout instead of stderr for logging and progress

stdout is the proper place for it. this also fixes the progress
bar in musl, which seems to not support using line buffering for
stderr.

src/apk.c

@@ -266,7 +266,6 @@ static void on_sigwinch(int s)
 
 static void setup_terminal(void)
 {
-	setvbuf(stderr, NULL, _IOLBF, BUFSIZ);
 	signal(SIGWINCH, on_sigwinch);
 	signal(SIGPIPE, SIG_IGN);
 }

src/print.c

@@ -35,7 +35,7 @@ int apk_get_screen_width(void)
 
 	if (apk_screen_width == 0) {
 		apk_screen_width = 50;
-		if (ioctl(STDERR_FILENO, TIOCGWINSZ, &w) == 0 &&
+		if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &w) == 0 &&
 		    w.ws_col > 50)
 			apk_screen_width = w.ws_col;
 	}
@@ -77,14 +77,14 @@ void apk_print_progress(size_t done, size_t total)
 	last_percent = percent;
 	apk_progress_force = 0;
 
-	fprintf(stderr, "\e7%3i%% [", percent);
+	fprintf(stdout, "\e7%3i%% [", percent);
 	for (i = 0; i < bar; i++)
-		fputc('#', stderr);
+		fputc('#', stdout);
 	for (; i < bar_width; i++)
-		fputc(' ', stderr);
-	fputc(']', stderr);
-	fflush(stderr);
-	fputs("\e8\e[0K", stderr);
+		fputc(' ', stdout);
+	fputc(']', stdout);
+	fflush(stdout);
+	fputs("\e8\e[0K", stdout);
 }
 
 int apk_print_indented(struct apk_indent *i, apk_blob_t blob)
@@ -144,11 +144,11 @@ void apk_log(const char *prefix, const char *format, ...)
 	va_list va;
 
 	if (prefix != NULL)
-		fprintf(stderr, "%s", prefix);
+		fprintf(stdout, "%s", prefix);
 	va_start(va, format);
-	vfprintf(stderr, format, va);
+	vfprintf(stdout, format, va);
 	va_end(va);
-	fprintf(stderr, "\n");
+	fprintf(stdout, "\n");
 	apk_progress_force = 1;
 }