Replace conform/list-header-symbols.pl with a Python script.

Continuing the move of test code from Perl to Python (which seems
uncontroversial, unlike dependencies on Python in the actual build of
glibc), this patch replaces conform/list-header-symbols.pl with a
Python script, as a first step in converting the conform/ tests.
(conform/glibcconform.py is an equivalent to GlibcConform.pm,
containing code that will be relevant to move than one of the conform/
scripts.)

Tested for x86_64, including verifying that the symbol lists generated
are identical to those generated by the Perl version.

	* conform/glibcconform.py: New file.
	* conform/list-header-symbols.py: Likewise.
	* conform/list-header-symbols.pl: Remove.
	* conform/Makefile (tests-special): Only add linknamespace tests
	if [PYTHON].
	($(linknamespace-symlists-tests)): Use list-header-symbols.py.

conform/list-header-symbols.py

@@ -0,0 +1,76 @@
+#!/usr/bin/python
+# Print a list of symbols exported by some headers that would
+# otherwise be in the user's namespace.
+# Copyright (C) 2018 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+#
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+import argparse
+
+import glibcconform
+
+# Extra symbols possibly not found through -aux-info but still
+# reserved by the standard: either data symbols, or symbols where the
+# standard leaves unspecified whether the identifier is a macro or
+# defined with external linkage.
+EXTRA_SYMS = {}
+EXTRA_SYMS['ISO'] = {'errno', 'setjmp', 'va_end'}
+EXTRA_SYMS['ISO99'] = EXTRA_SYMS['ISO'] | {'math_errhandling'}
+# stdatomic.h not yet covered by conformance tests; as per DR#419, all
+# the generic functions there or may not be defined with external
+# linkage (but are reserved in any case).
+EXTRA_SYMS['ISO11'] = EXTRA_SYMS['ISO99']
+# The following lists may not be exhaustive.
+EXTRA_SYMS['POSIX'] = (EXTRA_SYMS['ISO']
+                       | {'environ', 'sigsetjmp', 'optarg', 'optind', 'opterr',
+                          'optopt', 'tzname'})
+EXTRA_SYMS['XPG4'] = (EXTRA_SYMS['POSIX']
+                      | {'signgam', 'loc1', 'loc2', 'locs', 'daylight',
+                         'timezone'})
+EXTRA_SYMS['XPG42'] = EXTRA_SYMS['XPG4'] | {'getdate_err', 'h_errno'}
+EXTRA_SYMS['UNIX98'] = EXTRA_SYMS['XPG42']
+EXTRA_SYMS['XOPEN2K'] = (EXTRA_SYMS['POSIX']
+                         | {'signgam', 'daylight', 'timezone', 'getdate_err',
+                            'h_errno', 'in6addr_any', 'in6addr_loopback'})
+EXTRA_SYMS['POSIX2008'] = (EXTRA_SYMS['POSIX']
+                           | {'in6addr_any', 'in6addr_loopback'})
+EXTRA_SYMS['XOPEN2K8'] = (EXTRA_SYMS['POSIX2008']
+                          | {'signgam', 'daylight', 'timezone', 'getdate_err'})
+
+
+def main():
+    """The main entry point."""
+    parser = argparse.ArgumentParser(description='List exported symbols.')
+    parser.add_argument('--headers', metavar='HEADERS',
+                        help='list of headers')
+    parser.add_argument('--standard', metavar='STD',
+                        help='standard to use when processing headers')
+    parser.add_argument('--cc', metavar='CC',
+                        help='C compiler to use')
+    parser.add_argument('--flags', metavar='CFLAGS',
+                        help='Compiler flags to use with CC')
+    args = parser.parse_args()
+    fns = set()
+    compiler = '%s %s' % (args.cc, args.flags)
+    for header in args.headers.split():
+        fns |= glibcconform.list_exported_functions(compiler, args.standard,
+                                                    header)
+    fns |= EXTRA_SYMS[args.standard]
+    print('\n'.join(sorted(fn for fn in fns if not fn.startswith('_'))))
+
+
+if __name__ == '__main__':
+    main()