Fix etags reading of compressed files

Fix etags reading of compressed files

* lib-src/etags.c (O_CLOEXEC) [WINDOWSNT]: Define.
Include fcntl.h, for O_CLOEXEC.
(process_file_name): Don't use 'popen', whose streams cannot be
rewound.  Instead, uncompress the file to a temporary file,
created by 'etags_mktmp', and read from that as usual.
(etags_mktmp): New function.

* test/etags/ETAGS.good_1:
* test/etags/ETAGS.good_2:
* test/etags/ETAGS.good_3:
* test/etags/ETAGS.good_4:
* test/etags/ETAGS.good_5: Update to be consistent with latest
changes in etags.c regarding reading compressed files.