build: Fix libsoup dependency detection

The current check fails in multiple ways:

- the variable 'soupapiversion' needs to be checked in the pkg-config
  file; using get_variable() will only check inside the dependency's
  build system when used as a subproject
- grilo does not have a variable named 'soupapiversion' anyway; it's
  called 'soup_api_version'
- this is far from being idiomatic Meson

We need to split the check into two:

- check for pkg-config variables when using a system dependency
- check for a variable in the internal dependency when using grilo as a
  subproject

In order to make this work we are going to need the following MR in
Grilo:

  https://gitlab.gnome.org/GNOME/grilo/-/merge_requests/95

1 files changed, 5 insertions, 1 deletions

diff --git a/meson.build b/meson.build
index dce2069..0408142 100644
--- a/meson.build
+++ b/meson.build
@@ -57,7 +57,11 @@ gom_dep = dependency('gom-1.0', version: '>= 0.4', required: false)
 grilo_net_dep = dependency('grilo-net-0.3', version: '>= 0.3.0', required: false,
                            fallback: ['grilo', 'libgrlnet_dep'])
 if grilo_net_dep.found()
-  soup_api_version = grilo_net_dep.get_variable('soupapiversion', default_value: '2.4')
+  soup_api_version = grilo_net_dep.get_variable(
+      pkgconfig: 'soupapiversion',
+      internal: 'soupapiversion',
+      default_value: '2.4',
+  )
 else
   soup_api_version = '2.4'
 endif