Add unit tests that fail on x86

TODO.txt

@@ -31,6 +31,7 @@
   - 10000 [ dup number>string ] map describe in the UI
   - available-modules
   - :trace
+  - string-lines
 - auto-update browser and help when sources reload
 - mac intel: struct returns from objc methods
 - new windows don't always have focus, eg focus follows mouse

core/test/math/float.factor

@@ -19,6 +19,12 @@ USE: test
 
 [ t ] [ 134.3 >fixnum 134 = ] unit-test
 
+[ 3 ] [ 3.5 >bignum ] unit-test
+[ -3 ] [ -3.5 >bignum ] unit-test
+
+[ 3 ] [ 3.5 >fixnum ] unit-test
+[ -3 ] [ -3.5 >fixnum ] unit-test
+
 [ 2.1 ] [ -2.1 neg ] unit-test
 
 [ 1 ] [ 0.5 1/2 + ] unit-test