meson: fix rule for qemu-ga installer

The bindir variable is not available in the "glib" variable, which is an internal
dependency (created with "declare_dependency").  Use glib_pc instead, which contains
the variable as it is instantiated from glib-2.0.pc.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qga/meson.build

@@ -154,7 +154,7 @@ if targetos == 'windows'
                               qemu_ga_msi_arch[cpu],
                               qemu_ga_msi_vss,
                               '-D', 'BUILD_DIR=' + meson.project_build_root(),
-                              '-D', 'BIN_DIR=' + glib.get_variable('bindir'),
+                              '-D', 'BIN_DIR=' + glib_pc.get_variable('bindir'),
                               '-D', 'QEMU_GA_VERSION=' + config_host['QEMU_GA_VERSION'],
                               '-D', 'QEMU_GA_MANUFACTURER=' + config_host['QEMU_GA_MANUFACTURER'],
                               '-D', 'QEMU_GA_DISTRO=' + config_host['QEMU_GA_DISTRO'],