[vinagre] Remove bashism from configure.ac

[David King <davidk src gnome org>]

commit 85f0f181f14ef29dec3bcc145444c38d718f1d19
Author: Alexander Tsoy <alexander tsoy me>
Date:   Sun Oct 26 01:52:04 2014 +0400

    Remove bashism from configure.ac
    
    https://bugzilla.gnome.org/show_bug.cgi?id=739187

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f2d8294..73f933e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -119,7 +119,7 @@ AC_TYPE_UINT64_T
 # Checks for library functions. See vinagre/pty_open.c for usage.
 AC_CHECK_FUNCS([getpt posix_openpt grantpt unlockpt ptsname ptsname_r])
 
-AM_CONDITIONAL([VINAGRE_PTY_OPEN], [test "x$ac_cv_func_grantpt" == xyes])
+AM_CONDITIONAL([VINAGRE_PTY_OPEN], [test "x$ac_cv_func_grantpt" = "xyes"])
 
 AC_SEARCH_LIBS([strerror], [cposix])