Add a facility to skip running some test suites

With the build option SKIP_TEST_SUITES=..., the specified test suites
are built, but skipped when running tests. Usage:
    make check SKIP_TEST_SUITES=timing,gcm
or
    cmake -D SKIP_TEST_SUITES=timing,gcm ...

The list can be separated by any of space, comma or semicolon, and each
element can be a regular expression in ERE syntax except that "." stands
for itself. Skipping "foo" skips not only "foo" itself but also
any "foo.bar", but does not skip "foobar".
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index 7ffbd74..1c9dc1d 100755
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -10,13 +10,16 @@
 
 Execute all the test suites and print a summary of the results.
 
- run-test-suites.pl [[-v|--verbose] [VERBOSITY]]
+ run-test-suites.pl [[-v|--verbose] [VERBOSITY]] [--skip=SUITE[...]]
 
 Options:
 
   -v|--verbose        Print detailed failure information.
   -v 2|--verbose=2    Print detailed failure information and summary messages.
   -v 3|--verbose=3    Print detailed information about every test case.
+  --skip=SUITE[,SUITE...]
+                      Skip the specified SUITE(s). This option can be used
+                      multiple times.
 
 =cut
 
@@ -26,11 +29,13 @@
 use utf8;
 use open qw(:std utf8);
 
-use Getopt::Long qw(:config auto_help);
+use Getopt::Long qw(:config auto_help gnu_compat);
 use Pod::Usage;
 
 my $verbose = 0;
+my @skip_patterns = ();
 GetOptions(
+           'skip=s' => \@skip_patterns,
            'verbose|v:1' => \$verbose,
           ) or die;
 
@@ -41,6 +46,17 @@
 @suites = grep { !/\.c$/ && !/\.data$/ && -f } @suites;
 die "$0: no test suite found\n" unless @suites;
 
+# "foo" as a skip pattern skips "test_suite_foo" and "test_suite_foo.bar"
+# but not "test_suite_foobar".
+my $skip_re =
+    ( '\Atest_suite_(' .
+      join('|', map {
+          s/[ ,;]/|/g; # allow any of " ,;|" as separators
+          s/\./\./g; # "." in the input means ".", not "any character"
+          $_
+      } @skip_patterns) .
+      ')(\z|\.)' );
+
 # in case test suites are linked dynamically
 $ENV{'LD_LIBRARY_PATH'} = '../library';
 $ENV{'DYLD_LIBRARY_PATH'} = '../library';
@@ -50,6 +66,7 @@
 my ($failed_suites, $total_tests_run, $failed, $suite_cases_passed,
     $suite_cases_failed, $suite_cases_skipped, $total_cases_passed,
     $total_cases_failed, $total_cases_skipped );
+my $suites_skipped = 0;
 
 sub pad_print_center {
     my( $width, $padchar, $string ) = @_;
@@ -60,6 +77,12 @@
 for my $suite (@suites)
 {
     print "$suite ", "." x ( 72 - length($suite) - 2 - 4 ), " ";
+    if( $suite =~ /$skip_re/o ) {
+        print "SKIP\n";
+        ++$suites_skipped;
+        next;
+    }
+
     my $command = "$prefix$suite";
     if( $verbose ) {
         $command .= ' -v';
@@ -106,7 +129,10 @@
 
 print "-" x 72, "\n";
 print $failed_suites ? "FAILED" : "PASSED";
-printf " (%d suites, %d tests run)\n", scalar @suites, $total_tests_run;
+printf( " (%d suites, %d tests run%s)\n",
+        scalar(@suites) - $suites_skipped,
+        $total_tests_run,
+        $suites_skipped ? ", $suites_skipped suites skipped" : "" );
 
 if( $verbose > 1 ) {
     print "  test cases passed :", $total_cases_passed, "\n";
@@ -116,8 +142,11 @@
             "\n";
     print " of available tests :",
             ( $total_cases_passed + $total_cases_failed + $total_cases_skipped ),
-            "\n"
+            "\n";
+    if( $suites_skipped != 0 ) {
+        print "Note: $suites_skipped suites were skipped.\n";
     }
+}
 
 exit( $failed_suites ? 1 : 0 );