[libc] Changed mbstate struct (#143942)

Changed the mbstate variable from bits processed to bytes processed and
implemented isComplete().

Co-authored-by: Sriya Pratipati <[email protected]>

Author: sribee8

libc/src/__support/wchar/character_converter.cpp

@@ -18,7 +18,9 @@ namespace internal {
 
 CharacterConverter::CharacterConverter(mbstate *mbstate) { state = mbstate; }
 
-bool CharacterConverter::isComplete() {}
+bool CharacterConverter::isComplete() {
+  return state->bytes_processed == state->total_bytes;
+}
 
 int CharacterConverter::push(char8_t utf8_byte) {}
 

libc/src/__support/wchar/mbstate.h

@@ -18,7 +18,7 @@ namespace internal {
 
 struct mbstate {
   char32_t partial;
-  uint8_t bits_processed;
+  uint8_t bytes_processed;
   uint8_t total_bytes;
 };