Add iconv detection for meson build

Fixes https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/394

meson.build

@@ -1,6 +1,6 @@
 project('fontconfig', 'c',
   version: '2.14.2',
-  meson_version : '>= 0.57.0',
+  meson_version : '>= 0.60.0',
   default_options: [ 'buildtype=debugoptimized'],
 )
 
@@ -209,6 +209,20 @@ if cc.links(files('meson-cc-tests/solaris-atomic-operations.c'), name: 'Solaris
 endif
 
 
+# Check iconv support
+iconv_dep = []
+found_iconv = 0
+if host_machine.system() != 'windows'
+  iconv_dep = dependency('iconv', required: get_option('iconv'))
+  found_iconv = iconv_dep.found().to_int()
+else
+  if get_option('iconv').enabled()
+    warning('-Diconv was set but this is not functional on Windows.')
+  endif
+endif
+conf.set('USE_ICONV', found_iconv)
+deps += [iconv_dep]
+
 prefix = get_option('prefix')
 
 fonts_conf = configuration_data()
@@ -445,6 +459,7 @@ summary({
   'NLS': not get_option('nls').disabled(),
   'Tests': not get_option('tests').disabled(),
   'Tools': not get_option('tools').disabled(),
+  'iconv': found_iconv == 1,
 }, section: 'General', bool_yn: true, list_sep: ', ')
 summary({
   'Hinting': preferred_hinting,

meson_options.txt

@@ -13,6 +13,7 @@ option('tools', type : 'feature', value : 'auto', yield : true,
   description: 'Build command-line tools (fc-list, fc-query, etc.)')
 option('cache-build', type : 'feature', value : 'enabled',
   description: 'Run fc-cache on install')
+option('iconv', type: 'feature', value: 'disabled')
 
 # Defaults
 option('default-hinting', type: 'combo', choices: ['none', 'slight', 'medium', 'full'], value: 'slight',