autoninja.bat: have space suffix in ninja status

This improves output from ninja a bit on Windows when
NINJA_SUMMARIZE_BUILD is set.

The trailing space was removed in https://crrev.com/c/3400399.

Change-Id: Ifb14129a436a2673969f529d0c9143118dd87d6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3833272
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>

autoninja.bat

@@ -16,7 +16,7 @@ if not defined AUTONINJA_BUILD_ID (
 :: to trigger more verbose status updates. In particular this makes it possible
 :: to see how quickly process creation is happening - often a critical clue on
 :: Windows. The trailing space is intentional.
-if "%NINJA_SUMMARIZE_BUILD%" == "1" set NINJA_STATUS=[%%r processes, %%f/%%t @ %%o/s : %%es ]
+if "%NINJA_SUMMARIZE_BUILD%" == "1" set "NINJA_STATUS=[%%r processes, %%f/%%t @ %%o/s : %%es ] "
 
 :loop
 IF NOT "%1"=="" (