Patches pulled from https://todo.sr.ht/~lattis/muon/145 and merged into one below.

Athored by Sertonix <sertonix@posteo.net>.

diff --git a/src/external/pkgconfig_libpkgconf.c b/src/external/pkgconfig_libpkgconf.c
index ee4697f..c58c3cd 100644
--- a/src/external/pkgconfig_libpkgconf.c
+++ b/src/external/pkgconfig_libpkgconf.c
@@ -40,7 +40,11 @@ muon_pkgconf_init(struct workspace *wk, struct pkgconf_client *c, enum machine_k
 {
 	TracyCZoneAutoS;
 	c->personality = pkgconf_cross_personality_default();
-	pkgconf_client_init(&c->client, error_handler, NULL, c->personality);
+	pkgconf_client_init(&c->client, error_handler, NULL, c->personality
+#if defined(LIBPKGCONF_VERSION) && LIBPKGCONF_VERSION >= 20991
+		, NULL, NULL
+#endif
+	);
 
 	struct obj_array *pkg_config_path;
 	{
@@ -263,7 +267,11 @@ apply_variable(pkgconf_client_t *client, pkgconf_pkg_t *world, void *_ctx, int m
 	pkgconf_pkg_t *pkg = dep->match;
 
 	if (pkg != NULL) {
+#if defined(LIBPKGCONF_VERSION) && LIBPKGCONF_VERSION >= 20995
+		var = pkgconf_variable_eval_name(client, &pkg->vars, ctx->var);
+#else
 		var = pkgconf_tuple_find(client, &pkg->vars, ctx->var);
+#endif
 		if (var != NULL) {
 			*ctx->res = make_str(ctx->wk, var);
 			found = true;
diff --git a/subprojects/meson-tests/common/44 pkgconfig-gen/meson.build b/subprojects/meson-tests/common/44 pkgconfig-gen/meson.build
index ec2e339..00014ae 100644
--- a/subprojects/meson-tests/common/44 pkgconfig-gen/meson.build	
+++ b/subprojects/meson-tests/common/44 pkgconfig-gen/meson.build	
@@ -33,8 +33,10 @@ install_headers('simple.h')
 
 to_validate = []
 
-# generate for systems without a glib pc file
+# generate for systems without these pc files
 pkgg.generate(name: 'glib-2.0', dataonly: true)
+pkgg.generate(name: 'gio-2.0', dataonly: true)
+pkgg.generate(name: 'gobject-2.0', dataonly: true)
 
 if host_machine.system() != 'windows'
     # These libraries are not present in a windows default install.
diff --git a/subprojects/meson-tests/common/44 pkgconfig-gen/test.json b/subprojects/meson-tests/common/44 pkgconfig-gen/test.json
index eace7a8..8beee8c 100644
--- a/subprojects/meson-tests/common/44 pkgconfig-gen/test.json	
+++ b/subprojects/meson-tests/common/44 pkgconfig-gen/test.json	
@@ -15,7 +15,9 @@
     {"type": "file", "file": "usr/lib/pkgconfig/simple6.pc"},
     {"type": "file", "file": "usr/lib/pkgconfig/ct.pc"},
     {"type": "file", "file": "usr/lib/pkgconfig/ct0.pc"},
+    {"type": "file", "file": "usr/share/pkgconfig/gio-2.0.pc"},
     {"type": "file", "file": "usr/share/pkgconfig/glib-2.0.pc"},
+    {"type": "file", "file": "usr/share/pkgconfig/gobject-2.0.pc"},
     {"type": "file", "file": "usr/share/pkgconfig/libhello_nolib.pc"}
   ],
   "stdout": [