diff -Naur mysql-5.1.40-old/storage/innodb_plugin/plug.in mysql-5.1.40-new/storage/innodb_plugin/plug.in
--- mysql-5.1.40-old/storage/innodb_plugin/plug.in	2009-10-06 10:50:23.000000000 -0700
+++ mysql-5.1.40-new/storage/innodb_plugin/plug.in	2009-10-21 16:52:45.000000000 -0700
@@ -63,8 +63,9 @@
 		;;
   esac
   AC_SUBST(INNODB_DYNAMIC_CFLAGS)
-  AC_MSG_CHECKING(whether pthread_t can be used by GCC atomic builtins)
-  AC_TRY_RUN(
+  AC_CACHE_CHECK([whether pthread_t can be used by GCC atomic builtins],
+                 [ac_cv_have_decl_HAVE_ATOMIC_PTHREAD_T],
+  [AC_TRY_RUN(
     [
       #include <pthread.h>
       #include <string.h>
@@ -84,14 +85,18 @@
       }
     ],
     [
-      AC_DEFINE([HAVE_ATOMIC_PTHREAD_T], [1],
-                [pthread_t can be used by GCC atomic builtins])
       AC_MSG_RESULT(yes)
+      ac_cv_have_decl_HAVE_ATOMIC_PTHREAD_T=yes
     ],
     [
       AC_MSG_RESULT(no)
+      ac_cv_have_decl_HAVE_ATOMIC_PTHREAD_T=no
     ]
-    )
+    )])
+    if test "x$ac_cv_have_decl_HAVE_ATOMIC_PTHREAD"= "xyes" ; then
+      AC_DEFINE([HAVE_ATOMIC_PTHREAD_T], [1],
+                [pthread_t can be used by GCC atomic builtins])
+    fi
 
   # Try using solaris atomics on SunOS if GCC atomics are not available
   AC_CHECK_DECLS(