Remove unused init_unsigned_integer function.

As pointed out by Bernhard Reutner-Fischer, this function is unused
since the fix for PR 53796 in November 2017.

2018-09-07  Janne Blomqvist  <jb@gcc.gnu.org>

        * runtime/environ.c (init_unsigned_integer): Remove.

From-SVN: r264163

libgfortran/ChangeLog

+2018-09-07  Janne Blomqvist  <jb@gcc.gnu.org>
+
+	* runtime/environ.c (init_unsigned_integer): Remove.
+
 2018-09-05  Hans-Peter Nilsson  <hp@axis.com>
 
 	* io/async.h: Use __gthread_mutex_t, not pthread_mutex_t.

libgfortran/runtime/environ.c

@@ -98,25 +98,6 @@ init_integer (variable * v)
 }
 
 
-/* Initialize an integer environment variable which has to be positive.  */
-
-static void
-init_unsigned_integer (variable * v)
-{
-  char *p, *q;
-
-  p = getenv (v->name);
-  if (p == NULL)
-    return;
-
-  for (q = p; *q; q++)
-    if (!isdigit (*q))
-      return;
-
-  *v->var = atoi (p);
-}
-
-
 /* Initialize a boolean environment variable. We only look at the first
    letter of the value. */