Memory pools refactoring.

src/nxt_clang.h

@@ -207,6 +207,12 @@ nxt_bswap32(val)                                                              \
      |  ((val)               << 24))
 
 
+#define nxt_is_power_of_two(value)                                            \
+    ((((value) - 1) & (value)) == 0)
+
+#define nxt_lg2(value)                                                        \
+    (31 - __builtin_clz(value))
+
 
 #define                                                                       \
 nxt_align_size(d, a)                                                          \