[__GNU_LIBRARY__]: Use <string.h>.

lib-src/cvtmail.c

@@ -36,6 +36,10 @@ Boston, MA 02111-1307, USA.  */
 
 #include <stdio.h>
 
+#ifdef __GNU_LIBRARY__
+# include <string.h>
+#endif
+
 char *malloc ();
 char *realloc ();
 char *getenv ();

lib-src/sorted-doc.c

@@ -8,6 +8,10 @@
 #include <stdio.h>
 #include <ctype.h>
 
+#ifdef __GNU_LIBRARY__
+# include <string.h>
+#endif
+
 extern char *malloc ();
 char *xmalloc ();
 

lib-src/yow.c

@@ -14,6 +14,10 @@
 #include <ctype.h>
 #include <../src/paths.h>      /* For PATH_DATA.  */
 
+#ifdef __GNU_LIBRARY__
+# include <string.h>
+#endif
+
 #define BUFSIZE  80
 #define SEP      '\0'