Using HAVE_FOO_H and HAVE_FOO

[François-Xavier Coudert]

Hi,

I have written some code for inclusion into libgfortran (the gfortran 
runtime library), parts of which use Unix-only headers and functions, 
such as the <sys/types.h> and <signal.h> headers or the kill function.

In current code I could look at, such headers and functions are 
protected by ad hoc #ifdef (like HAVE_SYS_TYPES_H). However, I found no 
occurence of things such as HAVE_SIGNAL_H or HAVE_KILL (for <signal.h> 
and the kill library call). How can I add them to configure.ac (if I 
worked out the place correctly)?

Thanks,
FX