Revert "Revert "Pull the pthread_key_t functions out of pthread.c.""

This reverts commit 6260553d48f6fd87ca220270bea8bafdde5726ec

(Removing the accidental libm/Android.mk change.)

Change-Id: I6cddd9857c31facc05636e8221505b3d2344cb75
diff --git a/libc/include/sys/limits.h b/libc/include/sys/limits.h
index 5b127eb..2d0d11e 100644
--- a/libc/include/sys/limits.h
+++ b/libc/include/sys/limits.h
@@ -175,6 +175,12 @@
 #define  _POSIX_SAVED_IDS           1    /* saved user ids is a Linux feature */
 #define  _POSIX_JOB_CONTROL         1    /* job control is a Linux feature */
 
+#define _POSIX_THREAD_DESTRUCTOR_ITERATIONS 4 /* the minimum mandated by POSIX */
+#define PTHREAD_DESTRUCTOR_ITERATIONS 4
+#define _POSIX_THREAD_KEYS_MAX 128            /* the minimum mandated by POSIX */
+/* TODO: our PTHREAD_KEYS_MAX is currently too low to be posix compliant! */
+#define _POSIX_THREAD_THREADS_MAX 64          /* the minimum mandated by POSIX */
+#define PTHREAD_THREADS_MAX                   /* bionic has no specific limit */
 
 
 #endif