[java-atk-wrapper] Small fixup

[Federico Mena Quintero <federico src gnome org>]

commit 3845c7c286998c8de337637e4b3522fbe21c6b5e
Author: Fridrich Štrba <fridrich strba bluewin ch>
Date:   Fri Aug 24 11:11:38 2018 +0200

    Small fixup

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index df12ca4..c7f2735 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@ AC_ARG_ENABLE([modular-jar],
             [Build modular java-atk-wrapper jar])],
             [enable_modular_jar="$enableval"],
             [enable_modular_jar=no])
-AS_IF([test "enable_modular_jar" = "xyes"], [
+AS_IF([test "x$enable_modular_jar" = "xyes"], [
   JAVA_REQUIRED=9.0.0
 ], [
   JAVA_REQUIRED=1.7.0