configure: fix dependency of bitbang from dummy adapter

The commit bb2fc63 ("configure.ac: enable the Dummy adapter
by default") breaks the building dependency between bitbang code
and dummy adapter.

Fix it.

Change-Id: I47587ef61d6b57b2547f6c2600d8404cad87f584
Signed-off-by: Antonio Borneo <[email protected]>
Reported-by: Jonathan Forrest <[email protected]>
Fixes: bb2fc63 ("configure.ac: enable the Dummy adapter by default")
BugLink: https://sourceforge.net/p/openocd/tickets/446/
Reviewed-on: https://review.openocd.org/c/openocd/+/8682
Reviewed-by: Andrzej Sierżęga <[email protected]>
Tested-by: jenkins
Reviewed-by: Andy <[email protected]>

Author: borneoa

configure.ac

@@ -513,7 +513,7 @@ AS_IF([test "x$build_dmem" = "xyes"], [
   AC_DEFINE([BUILD_DMEM], [0], [0 if you don't want to debug via Direct Mem.])
 ])
 
-AS_IF([test "x$ADAPTER_VAR([dummy])" = "xyes"], [
+AS_IF([test "x$ADAPTER_VAR([dummy])" != "xno"], [
   build_bitbang=yes
 ])