Fix test information regarding default caching

Author: TGWDB

regression/cbmc/dereference-cache-flag/test-no-cache.desc

@@ -7,8 +7,7 @@ test.c
 --
 --
 This is just checking that the --symex-cache-dereferences flag actually turns
-dereference caching on and off. Note that dereference caching is turned ON
-by default in tests just to make sure that it doesn't break anything.
+dereference caching on and off.
 
 I would like to match the expression more precisely, but the order of
 comparisons for address of depends on platform-specific logic (unordered_xxx),

regression/cbmc/dereference-cache-flag/test-with-cache.desc

@@ -7,5 +7,4 @@ symex::dereference_cache!0#1 = 0
 --
 --
 This is just checking that the --symex-cache-dereferences flag actually
-turns dereference caching on Note that dereference caching is turned ON
-by default in tests just to make sure that it doesn't break anything.
+turns dereference caching on.

regression/cbmc/double_deref/README

@@ -25,9 +25,3 @@ double_deref_with_cast.desc -- a double-deref with an intervening cast (*(int*)*
 double_deref_with_member.desc -- a double-deref with an intervening member expression (p->field1->field2), should use a let-expression
 double_deref_with_pointer_arithmetic.desc -- a double-deref with intervening pointer arithmetic (p[idx1][idx2]), should use a let-expression
 *_single_alias.desc -- variants of the above where the first dereference points to a single possible object, so no let-expression is necessary
-
-Why no-dereference-cache?
--------------------------
-
-Because these tests test for specific VCCs to do with multiple nested complex
-dereferences and the dereference caching rewrites these.