Update from stable branch.

apps/apps.c

diff --git a/apps/apps.c b/apps/apps.c
index b04bfbd..b992a04 100644
--- a/apps/apps.c
+++ b/apps/apps.c
@@ -109,10 +109,12 @@
  *
  */
 
+#ifndef _POSIX_C_SOURCE
 #define _POSIX_C_SOURCE 2	/* On VMS, you need to define this to get
 				   the declaration of fileno().  The value
 				   2 is to make sure no function defined
 				   in POSIX-2 is left undefined. */
+#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

crypto/ui/ui_openssl.c

diff --git a/crypto/ui/ui_openssl.c b/crypto/ui/ui_openssl.c
index 1c2dcc4..9930439 100644
--- a/crypto/ui/ui_openssl.c
+++ b/crypto/ui/ui_openssl.c
@@ -122,7 +122,9 @@
  * sigaction and fileno included. -pedantic would be more appropriate for
  * the intended purposes, but we can't prevent users from adding -ansi.
  */
-#define _POSIX_C_SOURCE 1
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 2
+#endif
 #include <signal.h>
 #include <stdio.h>
 #include <string.h>