checkpatch: Disallow glib asserts in main code

Glib commit a6a875068779 (from 2013) made many of the glib assert
macros non-fatal if a flag is set.
This causes two problems:
  a) Compilers moan that your code is unsafe even though you've
     put an assert in before the point of use.
  b) Someone evil could, in a library, call
     g_test_set_nonfatal_assertions() and cause our assertions in
     important places not to fail and potentially allow memory overruns.

Ban most of the glib assertion functions (basically everything except
g_assert and g_assert_not_reached) except in tests/

This makes checkpatch gives an error such as:

  ERROR: Use g_assert or g_assert_not_reached
  #77: FILE: vl.c:4725:
  +    g_assert_cmpstr("Chocolate", >, "Cheese");
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170427165526.19836-1-dgilbert@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scripts/checkpatch.pl

@@ -2571,6 +2571,27 @@ sub process {
 		if ($line =~ /\bbzero\(/) {
 			ERROR("use memset() instead of bzero()\n" . $herecurr);
 		}
+		my $non_exit_glib_asserts = qr{g_assert_cmpstr|
+						g_assert_cmpint|
+						g_assert_cmpuint|
+						g_assert_cmphex|
+						g_assert_cmpfloat|
+						g_assert_true|
+						g_assert_false|
+						g_assert_nonnull|
+						g_assert_null|
+						g_assert_no_error|
+						g_assert_error|
+						g_test_assert_expected_messages|
+						g_test_trap_assert_passed|
+						g_test_trap_assert_stdout|
+						g_test_trap_assert_stdout_unmatched|
+						g_test_trap_assert_stderr|
+						g_test_trap_assert_stderr_unmatched}x;
+		if ($realfile !~ /^tests\// &&
+			$line =~ /\b(?:$non_exit_glib_asserts)\(/) {
+			ERROR("Use g_assert or g_assert_not_reached\n". $herecurr);
+		}
 	}
 
 	# If we have no input at all, then there is nothing to report on