Incorrect description of YACC

[Chris Long]

Hi,

The description of the variable YACC is incorrect.

If you include AC_PROG_YACC in configure.ac and run the resulting configure
script with --help, the output includes this description of the YACC
variable: "The `Yet Another C Compiler' implementation to use." YACC
actually stands for"Yet Another Compiler Compiler."

The source file containing this error is programs.m4.

It's a minor issue, but I think it's not just a cosmetic bug, because it
might confuse someone into thinking that yacc is similar to or a replacement
for gcc (which *is* a C compiler).

Anyway, thanks for all your hard work on autoconf.

- Chris