qemu-ga: Fixed paths issue with MSI build

Previously, if building out-of-tree, the MSI build would fail since
it wasn't able to find the needed files.

Signed-off-by: Leonid Bloch <leonid@daynix.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
* fixed up commit msg formating
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

Makefile

diff --git a/Makefile b/Makefile
index 9a4c3c6..f98a554 100644
--- a/Makefile
+++ b/Makefile
@@ -305,8 +305,8 @@
 
 $(QEMU_GA_MSI): config-host.mak
 
-$(QEMU_GA_MSI):  qga/installer/qemu-ga.wxs
-	$(call quiet-command,QEMU_GA_VERSION="$(QEMU_GA_VERSION)" QEMU_GA_MANUFACTURER="$(QEMU_GA_MANUFACTURER)" QEMU_GA_DISTRO="$(QEMU_GA_DISTRO)" \
+$(QEMU_GA_MSI):  $(SRC_PATH)/qga/installer/qemu-ga.wxs
+	$(call quiet-command,QEMU_GA_VERSION="$(QEMU_GA_VERSION)" QEMU_GA_MANUFACTURER="$(QEMU_GA_MANUFACTURER)" QEMU_GA_DISTRO="$(QEMU_GA_DISTRO)" BUILD_DIR="$(BUILD_DIR)" \
 	wixl -o $@ $(QEMU_GA_MSI_ARCH) $(QEMU_GA_MSI_WITH_VSS) $(QEMU_GA_MSI_MINGW_DLL_PATH) $<, "  WIXL  $@")
 else
 msi: