* libc/argz/envz_merge.c (envz_merge): Fix memory leak (Cygwin Coverity
	Scan CID 60023).
	* libc/ctype/iswalpha.c (iswalpha): Add bounds check to avoid
	out-of-bounds read from utf8 tables (CID 59949).
	* libc/locale/ldpart.c (__part_load_locale): Add 1 byte to size of lbuf.
	Write NUL into the last byte to accommodate split_lines (CID 60047).