selinux: drop unused macro

The macro _DEBUG_HASHES is nowhere used. The configuration DEBUG_HASHES
enables debugging of the SELinux hash tables, but the with an underscore
prefixed macro definition has no direct impact or any documentation.

Reported by clang [-Wunused-macros]
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/ss/policydb.c

@@ -41,8 +41,6 @@
 #include "mls.h"
 #include "services.h"
 
-#define _DEBUG_HASHES
-
 #ifdef DEBUG_HASHES
 static const char *symtab_name[SYM_NUM] = {
 	"common prefixes",