Prefer __nodiscard to __wur for readability.

[[nodiscard]] is the C++17 and C23 spelling, and even if you're not familiar with that yet, "wur" doesn't mean anything to anyone who isn't a libc maintainer!

Change-Id: I9a63b1e438a347a56535b01d6d05532ee052bcea
diff --git a/libc/private/bionic_mbstate.h b/libc/private/bionic_mbstate.h
index 0e5f861..fb85775 100644
--- a/libc/private/bionic_mbstate.h
+++ b/libc/private/bionic_mbstate.h
@@ -38,11 +38,11 @@
   (rv == BIONIC_MULTIBYTE_RESULT_ILLEGAL_SEQUENCE || \
    rv == BIONIC_MULTIBYTE_RESULT_INCOMPLETE_SEQUENCE)
 
-static inline __wur bool mbstate_is_initial(const mbstate_t* ps) {
+static inline __nodiscard bool mbstate_is_initial(const mbstate_t* ps) {
   return *(reinterpret_cast<const uint32_t*>(ps->__seq)) == 0;
 }
 
-static inline __wur size_t mbstate_bytes_so_far(const mbstate_t* ps) {
+static inline __nodiscard size_t mbstate_bytes_so_far(const mbstate_t* ps) {
   return
       (ps->__seq[2] != 0) ? 3 :
       (ps->__seq[1] != 0) ? 2 :
@@ -53,7 +53,7 @@
   ps->__seq[i] = static_cast<uint8_t>(byte);
 }
 
-static inline __wur uint8_t mbstate_get_byte(const mbstate_t* ps, int n) {
+static inline __nodiscard uint8_t mbstate_get_byte(const mbstate_t* ps, int n) {
   return ps->__seq[n];
 }
 
@@ -61,13 +61,13 @@
   *(reinterpret_cast<uint32_t*>(ps->__seq)) = 0;
 }
 
-static inline __wur size_t mbstate_reset_and_return_illegal(int _errno, mbstate_t* ps) {
+static inline __nodiscard size_t mbstate_reset_and_return_illegal(int _errno, mbstate_t* ps) {
   errno = _errno;
   mbstate_reset(ps);
   return BIONIC_MULTIBYTE_RESULT_ILLEGAL_SEQUENCE;
 }
 
-static inline __wur size_t mbstate_reset_and_return(size_t _return, mbstate_t* ps) {
+static inline __nodiscard size_t mbstate_reset_and_return(size_t _return, mbstate_t* ps) {
   mbstate_reset(ps);
   return _return;
 }