small patch re tcl8.1 and more

[Tom Tromey]

>> - snavigator/hyper/Makefile contains -Wall and -fwritable-strings,
>> both of which are gcc-specific options, but I don't know where the
>> Makefile got those options from. Note that those weren't there in
>> 4.5.1.

Syd> Got them from configure. There have to be checks in configure for
Syd> GNU C.

FYI, AC_PROG_CC checks for gcc.  You can use this in your
configure.in:

    if test "$GCC" = yes; then
	# Code for gcc here
    fi

Tom