crash_reporter: Fix a -Wmissing-field-initializers warning.

The fix is to use the C++ empty struct initialization {} instead of the
C-style {0}.

Bug: 27378717
Change-Id: I36896d1202bf30b5db5689ac13acaff3b3f1b30b
diff --git a/crash_collector_test.cc b/crash_collector_test.cc
index 7146638..a386cd1 100644
--- a/crash_collector_test.cc
+++ b/crash_collector_test.cc
@@ -95,7 +95,7 @@
 }
 
 TEST_F(CrashCollectorTest, FormatDumpBasename) {
-  struct tm tm = {0};
+  struct tm tm = {};
   tm.tm_sec = 15;
   tm.tm_min = 50;
   tm.tm_hour = 13;