[libc][Obvious] Fix missing entrypoints after moving to generic

Summary:
The previous patch moved the implementations of these to generic/ and
accidentally did not add the unlocked variants. This patch fixes that

libc/src/stdio/CMakeLists.txt

@@ -308,8 +308,11 @@ add_entrypoint_object(
 
 # These entrypoints have multiple potential implementations.
 add_stdio_entrypoint_object(feof)
+add_stdio_entrypoint_object(feof_unlocked)
 add_stdio_entrypoint_object(ferror)
+add_stdio_entrypoint_object(ferror_unlocked)
 add_stdio_entrypoint_object(clearerr)
+add_stdio_entrypoint_object(clearerr_unlocked)
 add_stdio_entrypoint_object(fopen)
 add_stdio_entrypoint_object(fclose)
 add_stdio_entrypoint_object(fread_unlocked)