build: Enable IFF format on Windows

Now that libiff and libilbm have been added to the MSYS2 repositories,
the plug-in can be built automatically on Windows.

build/windows/gitlab-ci/build-deps-crossroad.sh

@@ -40,6 +40,8 @@ crossroad install appstream-glib              \
                   gobject-introspection-runtime \
                   iso-codes                   \
                   libheif                     \
+                  libiff                      \
+                  libilbm                     \
                   libjxl                      \
                   $LIBMNG                     \
                   libmypaint mypaint-brushes  \

build/windows/gitlab-ci/build-gimp-msys2.sh

@@ -50,6 +50,8 @@ pacman --noconfirm -S --needed \
     mingw-w64-$MSYS2_ARCH-lensfun \
     mingw-w64-$MSYS2_ARCH-libarchive \
     mingw-w64-$MSYS2_ARCH-libheif \
+    mingw-w64-$MSYS2_ARCH-libiff \
+    mingw-w64-$MSYS2_ARCH-libilbm \
     mingw-w64-$MSYS2_ARCH-libjxl \
     mingw-w64-$MSYS2_ARCH-libmypaint \
     mingw-w64-$MSYS2_ARCH-libspiro \

meson.build

@@ -718,7 +718,13 @@ if have_qoi
   MIMEtypes += 'image/qoi'
 endif
 
-have_ilbm = cc.has_header('libilbm/ilbm.h', required: get_option('ilbm'))
+libiff = dependency('libiff', required: get_option('ilbm'))
+libilbm = dependency('libilbm', required: get_option('ilbm'))
+if libiff.found() and libilbm.found()
+  have_ilbm = true
+else
+  have_ilbm = cc.has_header('libilbm/ilbm.h', required: get_option('ilbm'))
+endif
 if have_ilbm
   MIMEtypes += 'image/x-ilbm'
 endif

plug-ins/common/meson.build

@@ -160,7 +160,12 @@ if have_qoi
   }
 endif
 
-if have_ilbm
+if libiff.found() and libilbm.found()
+  common_plugins_list += {
+    'name': 'file-iff',
+    'deps': [ gtk3, gegl, libiff, libilbm, ],
+  }
+elif have_ilbm
   common_plugins_list += {
     'name': 'file-iff',
     'deps': [ gtk3, gegl, ],