implement pthread_getattr_np
this function is mainly (purely?) for obtaining stack address
information, but we also provide the detach state since it's easy to
do anyway.
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 2086048..78b69cd 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -23,6 +23,8 @@
int detached;
unsigned char *map_base;
size_t map_size;
+ void *stack;
+ size_t stack_size;
void *start_arg;
void *(*start)(void *);
void *result;