core/crypto: Add a HAS_RAND_BYTES constant

core/crypto/rand_windows.odin

@@ -4,6 +4,9 @@ import win32 "core:sys/windows"
 import "core:os"
 import "core:fmt"
 
+HAS_RAND_BYTES :: true
+
+@(private)
 _rand_bytes :: proc(dst: []byte) {
 	ret := (os.Errno)(win32.BCryptGenRandom(nil, raw_data(dst), u32(len(dst)), win32.BCRYPT_USE_SYSTEM_PREFERRED_RNG))
 	if ret != os.ERROR_NONE {
@@ -21,7 +24,3 @@ _rand_bytes :: proc(dst: []byte) {
 		}
 	}
 }
-
-_has_rand_bytes :: proc() -> bool {
-	return true
-}