zstandard: pull in bug fixes from upstream 0.9.1 release (issue5884) stable

zstandard: pull in bug fixes from upstream 0.9.1 release (issue5884)

This changeset contains the meaningful code changes from
python-zstandard's 0.9.1 release. The main fix is to restore
support for compiling with mingw.

--- a/contrib/python-zstandard/setup.py	Wed Jun 06 21:19:42 2018 +0800
+++ b/contrib/python-zstandard/setup.py	Wed Jun 06 09:14:33 2018 -0700
@@ -33,7 +33,7 @@
 
 if '--warnings-as-errors' in sys.argv:
     WARNINGS_AS_ERRORS = True
-    sys.argv.remote('--warning-as-errors')
+    sys.argv.remove('--warning-as-errors')
 
 # Code for obtaining the Extension instance is in its own module to
 # facilitate reuse in other projects.

--- a/contrib/python-zstandard/setup_zstd.py	Wed Jun 06 21:19:42 2018 +0800
+++ b/contrib/python-zstandard/setup_zstd.py	Wed Jun 06 09:14:33 2018 -0700
@@ -123,6 +123,8 @@
         compiler_type = 'unix'
     elif compiler.compiler_type == 'msvc':
         compiler_type = 'msvc'
+    elif compiler.compiler_type == 'mingw32':
+        compiler_type = 'mingw32'
     else:
         raise Exception('unhandled compiler type: %s' %
                         compiler.compiler_type)
@@ -141,7 +143,7 @@
         extra_args.append('-DZSTD_LEGACY_SUPPORT=1')
 
     if warnings_as_errors:
-        if compiler_type == 'unix':
+        if compiler_type in ('unix', 'mingw32'):
             extra_args.append('-Werror')
         elif compiler_type == 'msvc':
             extra_args.append('/WX')