Checkstyle: Promote "NeedBraces" check to be an error.

Meant to do this in the original CL.

Bug: 999554
Change-Id: Ieadae26759407f0276062fa83d513659f9b5f091
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1807259
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#696856}

tools/android/checkstyle/chromium-style-5.0.xml

@@ -104,6 +104,7 @@
       <property name="severity" value="info"/>
     </module>
     <module name="NeedBraces">
+      <property name="severity" value="error"/>
       <property name="allowSingleLineStatement" value="true"/>
     </module>
     <module name="RegexpSinglelineJava">