Change name of MB_CUR_MAX implementation function.

Glibc calls theirs __ctype_get_mb_cur_max. Make ours match to cut down
on differences between bionic and glibc.

Bug: 11156955
Change-Id: Ib7231f01aa9676dff30aea0af25d597bfe07bc73
diff --git a/libc/bionic/locale.cpp b/libc/bionic/locale.cpp
index 4c3fd7f..ddb49ce 100644
--- a/libc/bionic/locale.cpp
+++ b/libc/bionic/locale.cpp
@@ -92,7 +92,7 @@
   g_locale.int_n_sign_posn = CHAR_MAX;
 }
 
-size_t __mb_cur_max() {
+size_t __ctype_get_mb_cur_max() {
   locale_t l = reinterpret_cast<locale_t>(pthread_getspecific(g_uselocale_key));
   if (l == nullptr || l == LC_GLOBAL_LOCALE) {
     return __bionic_current_locale_is_utf8 ? 4 : 1;