Define CHAR_MIN/MAX as macros

- This matches the definitions in libcucxx.

jitify2.hpp

@@ -3947,11 +3947,14 @@ JITIFY_DEFINE_C_AND_CXX_HEADERS(limits, R"(
 #define SCHAR_MIN   (-128)
 #define SCHAR_MAX   127
 #define UCHAR_MAX   255
-enum {
-    _JITIFY_CHAR_IS_UNSIGNED = ((char)-1 >= 0),
-    CHAR_MIN = (_JITIFY_CHAR_IS_UNSIGNED ? 0 : SCHAR_MIN),
-    CHAR_MAX = (_JITIFY_CHAR_IS_UNSIGNED ? UCHAR_MAX : SCHAR_MAX),
-};
+#define _JITIFY_CHAR_IS_UNSIGNED ('\xff' > 0)
+#if _JITIFY_CHAR_IS_UNSIGNED
+#define CHAR_MIN 0
+#define CHAR_MAX UCHAR_MAX
+#else
+#define CHAR_MIN SCHAR_MIN
+#define CHAR_MAX SCHAR_MAX
+#endif
 #define SHRT_MIN    (-SHRT_MAX - 1)
 #define SHRT_MAX    0x7fff
 #define USHRT_MAX   0xffff