No longer check for strdup or strndup for LIBOBJ replacement.

include/missing.h

@@ -78,12 +78,6 @@ int unsetenv(const char *);
 #ifndef HAVE_STRSIGNAL
 char *strsignal(int);
 #endif
-#ifndef HAVE_STRDUP
-char *strdup(const char *);
-#endif
-#ifndef HAVE_STRNDUP
-char *strndup(const char *, size_t);
-#endif
 #ifndef HAVE_GETGROUPLIST
 int getgrouplist(const char *name, gid_t basegid, gid_t *groups, int *ngroups);
 #endif