Drop workarounds for glibc 2.1 and Solaris 9.

Drop workarounds for glibc 2.1 and Solaris 9.

* gettext-tools/src/read-po-lex.c (po_lex_charset_set): Remove glibc 2.1 and
Solaris 9 workarounds.
* gettext-tools/src/recode-sr-latin.c (process): Likewise.
* gettext-tools/src/write-po.c (wrap): Likewise.
* gettext-tools/src/x-python.c (set_current_file_source_encoding): Likewise.
* gettext-tools/src/xgettext.c (main): Likewise.
* libtextstyle/gnulib-local/lib/iconv-ostream.oo.c (iconv_ostream::free,
iconv_ostream_create): Likewise.