[libsoup] build: test(1) uses '=' for string equality

[Dan Winship <danw src gnome org>]

commit 5225684baff2ec0f8ab3f7115df6718989609d7f
Author: Patrick Welche <prlw1 cam ac uk>
Date:   Wed Apr 13 01:29:14 2016 +0100

    build: test(1) uses '=' for string equality
    
    https://bugzilla.gnome.org/show_bug.cgi?id=764974

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 503dd2a..3f42770 100644
--- a/configure.ac
+++ b/configure.ac
@@ -344,7 +344,7 @@ if test "$with_gssapi" != "no"; then
            AC_DEFINE(LIBSOUP_HAVE_GSSAPI, 1, [Whether or not GSSAPI libs are available])
        fi
     else
-       if test "$with_gssapi" == "yes"; then
+       if test "$with_gssapi" = "yes"; then
            AC_MSG_ERROR([GSSAPI support requested but failed to found krb5-config. Try to set KRB5_CONFIG.])
        fi
     fi