Add missing cwd env var to grit_info and grit xmb

This fixes the build with compute_grit_inputs_for_analyze=true which regressed
after CL:
https://chromium.googlesource.com/chromium/src/+/93e774da116cc1bce515883fc28f012ccd905635

BUG=853961
R=dpranke

Change-Id: I48e9297107cc0e543f00f1d6fa7e347bc39e5de3
Reviewed-on: https://chromium-review.googlesource.com/1105485Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569099}

tools/grit/grit/tool/xmb.py

@@ -165,6 +165,8 @@ Other options:
     return 'Exports all translateable messages into an XMB file.'
 
   def Run(self, opts, args):
+    os.environ['cwd'] = os.getcwd()
+
     self.SetOptions(opts)
 
     limit_file = None

tools/grit/grit_info.py

@@ -110,6 +110,8 @@ def PrintUsage():
 
 
 def DoMain(argv):
+  os.environ['cwd'] = os.getcwd()
+
   parser = optparse.OptionParser()
   parser.add_option("--inputs", action="store_true", dest="inputs")
   parser.add_option("--outputs", action="store_true", dest="outputs")