meson: convert dummy Windows qga/qemu-ga target

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/Makefile b/Makefile
index e93ebf6..8d3c8d8 100644
--- a/Makefile
+++ b/Makefile
@@ -450,11 +450,6 @@
 qemu-keymap$(EXESUF): LIBS += $(XKBCOMMON_LIBS)
 qemu-keymap$(EXESUF): QEMU_CFLAGS += $(XKBCOMMON_CFLAGS)
 
-ifneq ($(EXESUF),)
-.PHONY: qga/qemu-ga
-qga/qemu-ga: qga/qemu-ga$(EXESUF) $(QGA_VSS_PROVIDER) $(QEMU_GA_MSI)
-endif
-
 module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak
 	$(call quiet-command,$(PYTHON) $< $@ \
 	$(addprefix $(SRC_PATH)/,$(patsubst %.mo,%.c,$(block-obj-m))), \
diff --git a/qga/meson.build b/qga/meson.build
index 33f6db2..2b91261 100644
--- a/qga/meson.build
+++ b/qga/meson.build
@@ -44,6 +44,7 @@
                  link_args: config_host['LIBS_QGA'].split(),
                  dependencies: [qemuutil, libudev],
                  install: true)
+all_qga = [qga]
 
 if targetos == 'windows'
   if 'CONFIG_QGA_VSS' in config_host
@@ -72,6 +73,9 @@
                               config_host['QEMU_GA_MSI_WITH_VSS'].split(),
                               config_host['QEMU_GA_MSI_MINGW_DLL_PATH'].split(),
                             ])
+    all_qga += [qga_msi]
     alias_target('msi', qga_msi)
   endif
 endif
+
+alias_target('qemu-ga', all_qga)
diff --git a/qga/vss-win32/meson.build b/qga/vss-win32/meson.build
index 1f39e05..780c461 100644
--- a/qga/vss-win32/meson.build
+++ b/qga/vss-win32/meson.build
@@ -14,6 +14,8 @@
                                cc.find_library('shlwapi'),
                                cc.find_library('uuid'),
                                cc.find_library('intl')])
+
+  all_qga += qga_vss
 endif
 
 # rules to build qga-vss.tlb