Add more tests for system calls to deal with bad buffers given to read and write

src/tests/userprog/read-bad-buf.ck

@@ -0,0 +1,10 @@
+# -*- perl -*-
+use strict;
+use warnings;
+use tests::tests;
+check_expected (IGNORE_KERNEL_FAULTS => 1, [<<'EOF']);
+(read-bad-buf) begin
+(read-bad-buf) open "sample.txt"
+read-bad-buf: exit(-1)
+EOF
+pass;