Some functions, like strdup() and strcasecmp(), are defined in

strings.h according to X/Open.

apps/apps.c

@@ -59,6 +59,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #define NON_MAIN

apps/ca.c

@@ -61,6 +61,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <ctype.h>
 #include <sys/types.h>
 #include <sys/stat.h>

crypto/engine/enginetest.c

@@ -58,6 +58,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <strings.h>
 #include <openssl/engine.h>
 #include <openssl/err.h>