Interpreting configure script's results

[John Yates]

Emacs seems to be rapidly acquiring dependencies on separate libraries.
Those listed as --without-xyz in the configure script's help appear to enable
uncontroversial additional capabilities that do not need to be requested
explicitly.  I contrast those with the --with-xyz options.

I build emacs on Ubuntu where I need to install a -dev package for emacs
to link against a library.  When configure displays its summary table I try
to understand the reason for any 'no' result.  Sometimes it is fairly obvious.
So recently when I saw

    Does Emacs use -lsqlite3?  no

I knew immediately that, even though I already had sqlite3 installed, I had
to add libsqlite3-dev.

Now consider that configure's help text shows

    --with-imagemagick      compile with ImageMagick image support
    --without-native-image-api
                          don't use native image APIs (GDI+ on Windows)

I take these to mean that one normally should not request Imagemagick
and that native image APIs will be used by default.  I use no version of
either of these options in my configuration.  My resulting summary is

    Does Emacs use imagemagick?  no
    Does Emacs use native APIs for images?  no

I expected the first 'no' and assumed that I should resolve the second.
But for the life of me I cannot figure out what -dev package is missing.
I have skimmed the configure script and have concluded that these
native APIs are available only on ns, w32 and haiku.  Does this mean
that image functionality is not supported on these three platforms? Do
I need to add --with-imagemagick?

Suggestion: Could configure's output be made more informative?
In particular, when some expected capability fails to be included
for lack of some header could that be called out?

/john