Prefixed macro with GPR_ a small var rename

include/grpc/support/useful.h

@@ -61,12 +61,15 @@
 /** Get the \a n-th bit of \a i */
 #define GPR_BITGET(i, n) (((i) & (1u << n)) != 0)
 
-#define HEXDIGIT_BITCOUNT_(x)                                    \
+#define GPR_INTERNAL_HEXDIGIT_BITCOUNT(x)                        \
   ((x) - (((x) >> 1) & 0x77777777) - (((x) >> 2) & 0x33333333) - \
    (((x) >> 3) & 0x11111111))
 
 /** Returns number of bits set in bitset \a i */
-#define GPR_BITCOUNT(x) \
+#define GPR_BITCOUNT(i)                          \
-  (((HEXDIGIT_BITCOUNT_(x) + (HEXDIGIT_BITCOUNT_(x) >> 4)) & 0x0F0F0F0F) % 255)
+  (((GPR_INTERNAL_HEXDIGIT_BITCOUNT(i) +         \
+     (GPR_INTERNAL_HEXDIGIT_BITCOUNT(i) >> 4)) & \
+    0x0F0F0F0F) %                                \
+   255)
 
 #endif  /* GRPC_SUPPORT_USEFUL_H */