qt: fix qt 6 tools detection for pkg-config

Add correct reading of pkgconfig-announced bindir and
pkgconfig-announced libexecdir. Will work only on 6.3+

mesonbuild/dependencies/qt.py

@@ -223,11 +223,18 @@ def __init__(self, name: str, env: 'Environment', kwargs: T.Dict[str, T.Any]):
             if prefix:
                 self.bindir = os.path.join(prefix, 'bin')
 
+        self.libexecdir = self.get_pkgconfig_host_libexecs(self)
+
     @staticmethod
     @abc.abstractmethod
     def get_pkgconfig_host_bins(core: PkgConfigDependency) -> T.Optional[str]:
         pass
 
+    @staticmethod
+    @abc.abstractmethod
+    def get_pkgconfig_host_libexecs(core: PkgConfigDependency) -> T.Optional[str]:
+        pass
+
     @abc.abstractmethod
     def get_private_includes(self, mod_inc_dir: str, module: str) -> T.List[str]:
         pass
@@ -405,13 +412,21 @@ def get_pkgconfig_host_bins(core: PkgConfigDependency) -> T.Optional[str]:
     def get_private_includes(self, mod_inc_dir: str, module: str) -> T.List[str]:
         return []
 
+    @staticmethod
+    def get_pkgconfig_host_libexecs(core: PkgConfigDependency) -> str:
+        return None
+
 
 class Qt5PkgConfigDependency(QtPkgConfigDependency):
 
     @staticmethod
     def get_pkgconfig_host_bins(core: PkgConfigDependency) -> str:
         return core.get_pkgconfig_variable('host_bins', [], None)
 
+    @staticmethod
+    def get_pkgconfig_host_libexecs(core: PkgConfigDependency) -> str:
+        return None
+
     def get_private_includes(self, mod_inc_dir: str, module: str) -> T.List[str]:
         return _qt_get_private_includes(mod_inc_dir, module, self.version)
 
@@ -420,7 +435,12 @@ class Qt6PkgConfigDependency(QtPkgConfigDependency):
 
     @staticmethod
     def get_pkgconfig_host_bins(core: PkgConfigDependency) -> str:
-        return core.get_pkgconfig_variable('host_bins', [], None)
+        return core.get_pkgconfig_variable('bindir', [], None)
+
+    @staticmethod
+    def get_pkgconfig_host_libexecs(core: PkgConfigDependency) -> str:
+        # Qt6 pkg-config for Qt defines libexecdir from 6.3+
+        return core.get_pkgconfig_variable('libexecdir', [], None)
 
     def get_private_includes(self, mod_inc_dir: str, module: str) -> T.List[str]:
         return _qt_get_private_includes(mod_inc_dir, module, self.version)