Why configure files don't find /usr/local based headers?

[Giorgos Keramidas]

On Tue, 22 Sep 2009 01:29:38 -0700, Yuri <yuri at rawbw.com> wrote:
> I noticed many times that configure files of various projects fail to
> find headers of third party packages under /usr/local/include.
> They run command line like this:
> gcc -c conftest.c
> and it doesn't find them without -I/usr/local/include.
>
> Is something misconfigured on my system? How to make this issue go away
> without modifying all configure files?

Because gcc in FreeBSD doesn't automatically include header files from
`/usr/local', unless you explicitly add the directory to the list of
include directories.

In other systems there may not be a `/usr/local/include' path at all.
For example, in my Debian installation there is no such directory.