libtextstyle: Don't use a C++ compiler.
* libtextstyle/gnulib-local/modules/fd-styled-ostream.diff: New file.
* libtextstyle/gnulib-local/modules/html-styled-ostream.diff: New file.
* libtextstyle/gnulib-local/modules/term-styled-ostream.diff: New file.
* libtextstyle/lib/Makefile.am (libtextstyle_la_LINK): Use the C compiler
always.
* libtextstyle/configure.ac: Remove LT_LANG([C++]), AC_PROG_CXX, and related
invocations.