beecrypt: arm assembly optimizations needs ARM instructions support

Fixes:
http://autobuild.buildroot.net/results/980/98034ebb086987fb8fc004672164f609f5a69543/
http://autobuild.buildroot.net/results/3bd/3bdba5cf7e901f8600e567b1b0eb0866d6dfc523/

So disable it for thumb(2)-only configurations (armv7m), similar to how we
do it for m68k coldfire.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/beecrypt/beecrypt.mk

@@ -22,6 +22,11 @@ ifeq ($(BR2_m68k_cf),y)
 BEECRYPT_CONF_OPTS += --enable-debug
 endif
 
+# arm asm optimization doesn't work for thumb-only
+ifeq ($(BR2_arm):$(BR2_ARM_CPU_HAS_ARM),y:)
+BEECRYPT_CONF_OPTS += --enable-debug
+endif
+
 ifeq ($(BR2_PACKAGE_BEECRYPT_CPP),y)
 BEECRYPT_DEPENDENCIES += icu
 BEECRYPT_CONF_OPTS += --with-cplusplus