Fix 'make install' from non-srcdir build

Commit b5ec5ce0 broke 'make install' from non source-dir build. Fix.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Makefile

@@ -193,7 +193,7 @@ endif
 
 install-sysconfig:
 	$(INSTALL_DIR) "$(sysconfdir)/qemu"
-	$(INSTALL_DATA) sysconfigs/target/target-x86_64.conf "$(sysconfdir)/qemu"
+	$(INSTALL_DATA) $(SRC_PATH)/sysconfigs/target/target-x86_64.conf "$(sysconfdir)/qemu"
 
 install: all $(if $(BUILD_DOCS),install-doc) install-sysconfig
 	$(INSTALL_DIR) "$(DESTDIR)$(bindir)"