fix cctype usage

According to the documentation, we should cast to unsigned char.
Anything negative is undefined behavior.

Utilities/Thread.cpp

@@ -96,6 +96,7 @@ DYNAMIC_IMPORT_RENAME("Kernel32.dll", SetThreadDescriptionImport, "SetThreadDesc
 #include "util/asm.hpp"
 #include "util/v128.hpp"
 #include "util/simd.hpp"
+#include "util/cctype.hpp"
 #include "util/sysinfo.hpp"
 #include "Emu/Memory/vm_locking.h"
 
@@ -185,9 +186,9 @@ bool IsDebuggerPresent()
 
 	for (const char* cp = status.data() + found + 10; cp <= status.data() + num_read; ++cp)
 	{
-		if (!std::isspace(*cp))
+		if (!utils::isspace(*cp))
 		{
-			return std::isdigit(*cp) != 0 && *cp != '0';
+			return utils::isdigit(*cp) != 0 && *cp != '0';
 		}
 	}