make_buildopts_h: Always include DETECT_DEADLOCKS

Since DETECT_DEADLOCKS is now split from DEBUG_THREADS, it must
always be included in buildopts.h instead of only when
ADD_CFLAGS_TO_BUILDOPTS_H is defined.  A SEGV will result otherwise.

Resolves: #719
(cherry picked from commit d1d80af0c0)

build_tools/make_buildopts_h

@@ -50,7 +50,7 @@ MENUSELECT_CFLAGS=$( echo "$MENUSELECT_CFLAGS" | \
 FILTER_OUT="\
 AO2_DEBUG|BETTER_BACKTRACES|BUILD_NATIVE|\
 COMPILE_DOUBLE|DEBUG_CHAOS|DEBUG_SCHEDULER|\
-DETECT_DEADLOCKS|DONT_OPTIMIZE|DUMP_SCHEDULER|\
+DONT_OPTIMIZE|DUMP_SCHEDULER|\
 LOTS_OF_SPANS|MALLOC_DEBUG|RADIO_RELAX|\
 REBUILD_PARSERS|REF_DEBUG|USE_HOARD_ALLOCATOR"