Optimize fileno_unlocked

Implement fileno_unlocked without FLOCK.

Issue: #I7L16Z
Test: libctest, benchmark
Signed-off-by: Nlitao <litao@kaihong.com>
Change-Id: Iee03e7a561e5bedde74054910a0e7ecebf7afe67

musl_src.gni

@@ -2214,6 +2214,7 @@ musl_src_porting_file = [
   "src/misc/aarch64/syscall.s",
   "src/stdlib/strtod.c",
   "src/stdio/vfscanf.c",
+  "src/stdio/fileno.c",
 ]
 
 musl_inc_hook_files = [

porting/linux/user/src/stdio/fileno.c

+#include "stdio_impl.h"
+#include <errno.h>
+
+int fileno_unlocked(FILE *f)
+{
+	int fd = f->fd;
+	if (fd < 0) {
+		errno = EBADF;
+		return -1;
+	}
+	return fd;
+}
+
+int fileno(FILE *f)
+{
+	FLOCK(f);
+	int fd = fileno_unlocked(f);
+	FUNLOCK(f);
+	return fd;
+}