Port ctags+etags build to Sun C 5.12.

Port ctags+etags build to Sun C 5.12.

* .bzrignore: Remove lib-src/ctags.c.
* lib-src/Makefile.in (etags_args): Remove, replacing with ...
(etags_cflags, etags_libs): New macros.  All uses changed.
(ctags${EXEEXT}): Don't compile etags.c, as compiling etags.c in
parallel (once for ctags, once for etags) breaks parallel makes
with compilers that use the source file name to name temporaries,
such as Sun C 5.12.  Instead, compile ctags.c.
* lib-src/ctags.c: New file.