Taken from alpine, with additional fixes
https://bugs.gentoo.org/713306

--- a/libhashkit/fnv_64.cc
+++ b/libhashkit/fnv_64.cc
@@ -37,8 +37,9 @@
 
 
 #include <libhashkit/common.h>
+#include <limits.h>
 
-#if __WORDSIZE == 64 && defined(HAVE_FNV64_HASH)
+#if (LONG_BIT == 64) && defined(HAVE_FNV64_HASH)
 
 /* FNV hash'es lifted from Dustin Sallings work */
 static uint64_t FNV_64_INIT= 0xcbf29ce484222325;
--- a/libhashkit/has.cc
+++ b/libhashkit/has.cc
@@ -37,6 +37,7 @@
 
 
 #include <libhashkit/common.h>
+#include <limits.h>
 
 bool libhashkit_has_algorithm(const hashkit_hash_algorithm_t algo)
 {
@@ -44,7 +45,7 @@
   {
   case HASHKIT_HASH_FNV1_64:
   case HASHKIT_HASH_FNV1A_64:
-#if __WORDSIZE == 64 && defined(HAVE_FNV64_HASH)
+#if (LONG_BIT == 64) && defined(HAVE_FNV64_HASH)
     return true;
 #else
     return false;
--- a/libmemcachedutil/pool.cc
+++ b/libmemcachedutil/pool.cc
@@ -42,6 +42,7 @@
 #include <cerrno>
 #include <pthread.h>
 #include <memory>
+#include <string.h>
 
 struct memcached_pool_st
 {
--- a/libtest/cmdline.cc
+++ b/libtest/cmdline.cc
@@ -61,7 +61,7 @@
 #include <algorithm>
 #include <stdexcept>
 
-#ifndef __USE_GNU
+#ifndef _GNU_SOURCE
 static char **environ= NULL;
 #endif
 
@@ -201,7 +201,7 @@
 
   fatal_assert(posix_spawnattr_setsigmask(&spawnattr, &mask) == 0);
 
-#if defined(POSIX_SPAWN_USEVFORK) || defined(__linux__)
+#if defined(POSIX_SPAWN_USEVFORK) || defined(__GLIBC__)
   // Use USEVFORK on linux
   flags |= POSIX_SPAWN_USEVFORK;
 #endif