test can be allowed to run if fopen() is capable of fopen()ing

three additional files once that we have already open()ed the
big bunch of file descriptors.

tests/libtest/lib518.c

@@ -67,21 +67,21 @@ static void close_file_descriptors(void)
 
 static int fopen_works(void)
 {
-  FILE *fpa[SAFETY_MARGIN];
+  FILE *fpa[3];
   int i;
   int ret = 1;
 
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     fpa[i] = NULL;
   }
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     fpa[i] = fopen(DEV_NULL, "r");
     if (fpa[i] == NULL) {
       ret = 0;
       break;
     }
   }
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     if (fpa[i] != NULL)
       fclose(fpa[i]);
   }

tests/libtest/lib537.c

@@ -68,21 +68,21 @@ static void close_file_descriptors(void)
 
 static int fopen_works(void)
 {
-  FILE *fpa[SAFETY_MARGIN];
+  FILE *fpa[3];
   int i;
   int ret = 1;
 
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     fpa[i] = NULL;
   }
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     fpa[i] = fopen(DEV_NULL, "r");
     if (fpa[i] == NULL) {
       ret = 0;
       break;
     }
   }
-  for (i = 0; i < SAFETY_MARGIN; i++) {
+  for (i = 0; i < 3; i++) {
     if (fpa[i] != NULL)
       fclose(fpa[i]);
   }