[gtk+] build: Fix sassc detection

[Emmanuele Bassi <ebassi src gnome org>]

commit bee29ea6c80d4539d359cebb0d0a3713695e8318
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Sat Apr 1 16:39:21 2017 +0100

    build: Fix sassc detection

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 9be2809..51b2d34 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1874,7 +1874,7 @@ AC_SUBST(GDK_HIDDEN_VISIBILITY_CFLAGS)
 
 AC_PATH_PROG([SASSC], [sassc])
 AC_ARG_VAR(SASSC)
-AM_CONDITIONAL([REBUILD_SCSS], [test "xSASSC" != x])
+AM_CONDITIONAL([REBUILD_SCSS], [test "x${SASSC}" != x])
 
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