Added check for pthread.h (reported by Steven Edwards).
Removed init_done check, the process heap is now created before kernel
is loaded anyway.

diff --git a/configure.ac b/configure.ac
index acb71d3..b8852ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1020,6 +1020,7 @@
 	netinet/tcp.h \
 	netinet/tcp_fsm.h \
 	openssl/ssl.h \
+	pthread.h \
 	pty.h \
 	pwd.h \
 	regex.h \