cr_assert(): Paste condition as a string cause error

[MrZLeo]

In cr_assert(), criterion paste condition as a string directly, preventing use a simple bool expression:

In file included from ../subprojects/criterion/include/criterion/new/assert.h:464,
                 from ../test/rbtree.c:4:
../test/rbtree.c: In function ‘rb_insert_color_rr_inbalance_impl’:
../subprojects/criterion/include/criterion/new/../internal/new_asserts.h:54:20: error: pasting "CRI_ASSERT_TEST_SPECIFIER_" and "!" does not give a valid preprocessing token
   54 |     CRI_IF_DEFINED(CRI_ASSERT_TEST_SPECIFIER_ ## Spec,  \
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
../subprojects/criterion/include/criterion/new/../internal/new_asserts.h:82:23: note: in expansion of macro ‘CRI_ASSERT_SPECIFIER’
   82 |         cri_cond_un = CRI_ASSERT_SPECIFIER(Condition);                          \
      |                       ^~~~~~~~~~~~~~~~~~~~
../subprojects/criterion/include/criterion/new/../internal/new_asserts.h:173:5: note: in expansion of macro ‘CRI_ASSERT_CALL’
  173 |     CRI_ASSERT_CALL(File, Line, Fail, CR_VA_HEAD(__VA_ARGS__), , CR_VA_TAIL(__VA_ARGS__))
      |     ^~~~~~~~~~~~~~~
../subprojects/criterion/include/criterion/new/../internal/new_asserts.h:179:27: note: in expansion of macro ‘cr_assert_user’
  179 | #define cr_assert(...)    cr_assert_user(__FILE__, __LINE__, criterion_abort_test, __VA_ARGS__)
      |                           ^~~~~~~~~~~~~~
../test/rbtree.c:104:5: note: in expansion of macro ‘cr_assert’
  104 |     cr_assert(!!rb_is_black(&(node2->rb)), "Root node should be black");
      |     ^~~~~~~~~

Here what I am doing is call rb_is_black() and assert it should be true. but in this case, compile error evoked. The reason is clear that we paste the whole condition as a string together with CRI_ASSERT_TEST_SPECIFIER_, and ! is not a valid token.

An ugly workaround is:

    cr_assert(
        eq(i32, true, rb_is_black(&(node2->rb))),
        "Root node should be black"
    );

which makes it a comparison between my function and the true.