Use with rather than enable for cims switch.

It pulls external library and does not just switch some internal
feature.

Add proper bool logic to the conditional because by default
we consider it requested unless proven otherwise.
Sort out internal/external switch to also support system-libs switch.

configure.in

@@ -519,14 +519,14 @@ AC_ARG_ENABLE(release-build,
          See http://wiki.documentfoundation.org/DevBuild]),
 ,)
 
-AC_ARG_ENABLE(cmis,
-    AS_HELP_STRING([--disable-cmis],
-        [Disable CMIS experimental feature.]),
-,enable_cmis=yes)
-
 dnl ===================================================================
 dnl Optional Packages (--with/without-)
 dnl ===================================================================
+AC_ARG_WITH(cmis,
+    AS_HELP_STRING([--without-cmis],
+        [Disable experimental CMIS interface.]),
+)
+
 AC_ARG_WITH(gnu-patch,
     AS_HELP_STRING([--with-gnu-patch],
         [Specify location of GNU patch on Solaris or FreeBSD.]),
@@ -4628,7 +4628,7 @@ dnl ===================================================================
 dnl Check for system libcmis
 dnl ===================================================================
 AC_MSG_CHECKING([which libcmis to use])
-if test -n "$with_system_libcmis" -a "$with_system_libcmis" = "yes"; then
+if test "x$with_system_libcmis" != "xno" -o -n "$with_system_libs"; then
     AC_MSG_RESULT([external])
     SYSTEM_LIBCMIS=YES
     PKG_CHECK_MODULES( LIBCMIS, libcmis-0.2 )
@@ -7029,7 +7029,7 @@ fi
 AC_SUBST(ENABLE_CAIRO_CANVAS)
 
 ENABLE_CMIS="FALSE"
-if test "$enable_cmis" = "yes" ; then
+if test "x$with_cmis" != "xno" ; then
    ENABLE_CMIS="TRUE"
 fi
 AC_SUBST(ENABLE_CMIS)