[gnome-initial-setup/wjt/vendor-conf-path-option: 1/3] driver: Fix build with -Dvendor-conf-file

[Will Thompson <wjt src gnome org>]

commit d9b3ff3e52822df8c230ec9d71f2478190e7f881
Author: Will Thompson <wjt endlessm com>
Date:   Tue Jun 16 17:03:25 2020 +0100

    driver: Fix build with -Dvendor-conf-file
    
    Using #if on a stringy-typed macro gives:
    
        In file included from ../gnome-initial-setup/gis-driver.c:22:
        ../gnome-initial-setup/gis-driver.c: In function ‘report_conf_error_if_needed’:
        ./config.h:36:26: error: token ""/sysroot/home/wjt/src/gnome/gnome-initial-setup/vendor.ini"" is not 
valid in preprocessor expressions
         #define VENDOR_CONF_FILE "/sysroot/home/wjt/src/gnome/gnome-initial-setup/vendor.ini"
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        ./config.h:36:26: note: in definition of macro ‘VENDOR_CONF_FILE’
         #define VENDOR_CONF_FILE "/sysroot/home/wjt/src/gnome/gnome-initial-setup/vendor.ini"
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 gnome-initial-setup/gis-driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gnome-initial-setup/gis-driver.c b/gnome-initial-setup/gis-driver.c
index ae42d52c..a9afd6ab 100644
--- a/gnome-initial-setup/gis-driver.c
+++ b/gnome-initial-setup/gis-driver.c
@@ -546,7 +546,7 @@ report_conf_error_if_needed (const gchar *group,
                              const gchar *key,
                              const GError *error)
 {
-#if VENDOR_CONF_FILE
+#ifdef VENDOR_CONF_FILE
   const char *file = VENDOR_CONF_FILE;
 #else
   const char *file = "vendor.conf";