[gdk-pixbuf/ebassi/for-master] build: Use `type:array` for builtin_loaders option

[Emmanuele Bassi <ebassi src gnome org>]

commit dac7bbac2ed73449a1cfc02745dbcd73f90f0538
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Apr 8 17:28:02 2021 +0100

    build: Use `type:array` for builtin_loaders option
    
    This gives us an actual array, and lets Meson deal with the argument
    parsing. It also gives us a default value that we can specify in the
    meson_options.txt.

 meson.build       | 12 +++---------
 meson_options.txt |  7 ++++---
 2 files changed, 7 insertions(+), 12 deletions(-)
---
diff --git a/meson.build b/meson.build
index b84d804c7..0241fcde0 100644
--- a/meson.build
+++ b/meson.build
@@ -237,21 +237,15 @@ else
 endif
 gdk_pixbuf_conf.set('USE_GMODULE', build_modules)
 
-# We want these loaders to be built into gdk-pixbuf unless
-# the builtin_loaders option specifies otherwise
-default_builtin_loaders = [ 'png', 'jpeg' ]
-
 # Check which loaders should be built into gdk-pixbuf
-builtin_loaders = get_option('builtin_loaders').split(',')
+builtin_loaders = get_option('builtin_loaders')
 
 # If 'all' is specified for builtin_loaders, build all
 # buildable loaders into gdk-pixbuf
 builtin_all_loaders = false
-if builtin_loaders == [ 'all' ]
+if builtin_loaders.contains('all')
   builtin_all_loaders = true
-elif builtin_loaders == [ 'default' ]
-  builtin_loaders = default_builtin_loaders
-elif builtin_loaders == [ 'none' ]
+elif builtin_loaders.contains('none')
   builtin_loaders = []
 endif
 
diff --git a/meson_options.txt b/meson_options.txt
index 0705e8cde..0ee6718bf 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -11,9 +11,10 @@ option('jpeg',
        type: 'boolean',
        value: true)
 option('builtin_loaders',
-       description: 'Comma-separated list of loaders to build into gdk-pixbuf, or "default", or "none", or 
"all" to build all buildable loaders into gdk-pixbuf',
-       type: 'string',
-       value: 'default')
+       description: 'Comma-separated list of loaders to build into gdk-pixbuf',
+       type: 'array',
+       choices: ['all', 'none', 'windows', 'png', 'bmp', 'gif', 'ico', 'ani', 'jpeg', 'pnm', 'tiff', 'xpm', 
'xbm', 'tga', 'icns', 'qtif'],
+       value: ['png', 'jpeg'])
 option('gtk_doc',
        description: 'Whether to generate the API reference',
        type: 'boolean',