Bug 1637957 - ensure consistent output when checking for linker kind; r=firefox-build-system-reviewers,rstewart

If we don't do this, configure will happily think the linker kind is
"unknown", which then causes problems downstream.

Differential Revision: https://phabricator.services.mozilla.com/D75300

build/moz.configure/toolchain.configure

@@ -2065,6 +2065,9 @@ def select_linker(linker, c_compiler, developer_options, enable_gold,
         # specific to it on stderr when it fails to process --version.
         env = dict(os.environ)
         env['LD_PRINT_OPTIONS'] = '1'
+        # Some locales might not print out the strings we are looking for, so
+        # ensure consistent output.
+        env['LC_ALL'] = 'C'
         retcode, stdout, stderr = get_cmd_output(*cmd, env=env)
         if retcode == 1 and 'Logging ld64 options' in stderr:
             kind = 'ld64'