grok_bin_oct_hex: Simplify flag

It's easier to understand and code if each flag name is for a single
flag.

Author: khwilliamson

numeric.c

@@ -400,7 +400,8 @@ Perl_grok_bin_oct_hex(pTHX_ const char *start,
     *flags = 0;
 
     const bool allow_underscores =
-             cBOOL(input_flags & PERL_SCAN_ALLOW_UNDERSCORES);
+             cBOOL(input_flags & ( PERL_SCAN_ALLOW_UNDERSCORES
+                                  |PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES));
     const char * s = start;
     const char * e = start + *len_p;
 
@@ -555,8 +556,8 @@ Perl_grok_bin_oct_hex(pTHX_ const char *start,
                 /* Don't allow a leading underscore if the only-medial bit is
                  * set */
             && (   LIKELY(s > s0)
-                || UNLIKELY((input_flags & PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES)
-                                        != PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES)))
+                || UNLIKELY(! (  input_flags
+                               & PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES))))
         {
             ++s;
 

perl.h

@@ -8345,7 +8345,8 @@ EXTERN_C int flock(int fd, int op);
 #  define PERL_SCAN_SILENT_OVERFLOW                 0x80
 
 /* Forbid a leading underscore, which the other one doesn't */
-#  define PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES (0x100|PERL_SCAN_ALLOW_UNDERSCORES)
+#  define PERL_SCAN_ALLOW_MEDIAL_UNDERSCORES        0x100
+
 #endif