std_darwin.modulemap: Break cyclic module dependencies

With the latest MacOSX15.0.sdk, Clang complains about a "cyclic
dependency in module 'std': std -> _wctype -> __wctype -> std".
Break this cycle by deleting the module for ctype.h in libc++,
it only includes ctype.h from the C library which has its own
module definition.

Closes #16219

include/cling/std_darwin.modulemap

@@ -429,10 +429,6 @@ module std_complex_h [system] {
   header "complex.h"
   export *
 }
-module std_ctype_h [system] {
-  header "ctype.h"
-  export *
-}
 module std_errno_h [system] {
   header "errno.h"
   export *