Cause B programs to fail on startup if they detect alignment issues.

lang/b/lib/b.h

@@ -14,6 +14,8 @@
 #error Unsupported EM_PSIZE
 #endif
 
+#define MASK ((1<<SHIFT)-1)
+
 extern FILE* input_unit;
 extern FILE* output_unit;
 

lang/b/lib/main.c

@@ -173,6 +173,8 @@ void patch_addresses(uintptr_t** p)
     while (*p)
     {
         uintptr_t* q = *p++;
+		if (*q & MASK)
+			abort();
         *q >>= SHIFT;
     }
 }