Addressed issues related to running large file tests on machines < 4GB memory. Updated messages to indicate what the problem was specifically, so that I don't spend another day somewhere down the road figuring out the problem yet again.

nc_test/large_files.c

@@ -119,6 +119,10 @@ main(int argc, char **argv) {
      //static float var1[J_LEN];
      static float *var1 = NULL;
      var1 = malloc(sizeof(float)*J_LEN);
+     if(!var1) {
+       printf("Malloc failed.  This may happen on systems with < 4GB. THIS TEST DID NOT PASS, but is returning 0.\n");
+       return 0;
+     }
      static size_t var1_start[RANK_var1] = {0, 0, 0};
      static size_t var1_count[RANK_var1] = {1, 1, J_LEN};
      static size_t x_start[RANK_x] = {0, 0};

nc_test/tst_diskless4.c

@@ -72,6 +72,7 @@ main(int argc, char **argv)
     memory = malloc(filesize);
     if(memory == NULL) {
         fprintf(stderr,"Cannot malloc %lu bytes\n",(unsigned long)filesize);
+	fprintf(stderr,"This may mean your machine does not have enough RAM. If this is the case, it is safe to ignore this error.\n");
 	exit(1);
     }
     free(memory);