patman: Respect include directive on Git config lookup

People may put their user name and email in a local config file and
reference it by the include.* directives, however `git config --global`
doesn't look up the included configs by default.

Enable the --includes option explicitly to support such use cases.

Signed-off-by: Fei Shao <fshao@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/gitutil.py b/tools/patman/gitutil.py
index 6700057..b0a12f2 100644
--- a/tools/patman/gitutil.py
+++ b/tools/patman/gitutil.py
@@ -651,7 +651,7 @@
     Returns:
         User name found in .gitconfig file, or None if none
     """
-    uname = command.output_one_line('git', 'config', '--global', 'user.name')
+    uname = command.output_one_line('git', 'config', '--global', '--includes', 'user.name')
     return uname
 
 
@@ -661,7 +661,7 @@
     Returns:
         User's email found in .gitconfig file, or None if none
     """
-    uemail = command.output_one_line('git', 'config', '--global', 'user.email')
+    uemail = command.output_one_line('git', 'config', '--global', '--includes', 'user.email')
     return uemail