crc32c: Fix AIX compulation - ALIGN defined

ALIGN was defined already:

mysys/crc32/crc32c.cc:390: warning: "ALIGN" redefined
 #define ALIGN(n, m)     ((n + ((1 << m) - 1)) & ~((1 << m) - 1))

In file included from /root/aix/build/include/my_global.h:543,
                 from /root/aix/build/mysys/crc32/crc32c.cc:22:
/opt/freeware/lib/gcc/powerpc-ibm-aix7.1.0.0/8/include-fixed/sys/socket.h:788: note: this is the location of the previous definition
 #define ALIGN(p)                (ulong)((caddr_t)(p) + MACHINE_ALIGNMENT - 1 - \

mysys/crc32/crc32c.cc

@@ -386,6 +386,10 @@ uint32_t ExtendImpl(uint32_t crc, const char* buf, size_t size) {
   const uint8_t *e = p + size;
   uint64_t l = crc ^ 0xffffffffu;
 
+#ifdef ALIGN
+#undef ALIGN
+#endif
+
 // Align n to (1 << m) byte boundary
 #define ALIGN(n, m)     ((n + ((1 << m) - 1)) & ~((1 << m) - 1))