update gettext test to use new intl dependency

Tests that we find something sensible for intl, capable of producing
binaries using gettext() to translate stuff.

No more need to manually check headers and *maybe* include the intl
library, which we were doing before; the new dependency actually
simplifies the existing test, and should simplify users' build files
too...

test cases/frameworks/6 gettext/meson.build

@@ -10,8 +10,9 @@ if not xgettext.found()
   error('MESON_SKIP_TEST xgettext not found.')
 endif
 
-if not meson.get_compiler('c').has_header('libintl.h')
-  error('MESON_SKIP_TEST libintl.h not found.')
+intl = dependency('intl', required: false)
+if not intl.found()
+  error('MESON_SKIP_TEST libintl/gettext functions not found.')
 endif
 
 i18n = import('i18n')

test cases/frameworks/6 gettext/src/meson.build

@@ -1,2 +1,2 @@
 executable('intlprog', 'intlmain.c', install : true,
-  dependencies : meson.get_compiler('c').find_library('intl', required : false))
+  dependencies : intl)