odrefresh: Avoid uninitialized usage

update_cache_info_only was only setting set to 'true' in one certain
situation, but then read from in another one.  We make sure it's
initialized before it ever gets read.

Test: TreeHugger
Bug: 211458160
Change-Id: I0be42699aeccf476619ef7d8b44b1037b5a0dd57
diff --git a/odrefresh/odrefresh.h b/odrefresh/odrefresh.h
index bc6a68f..88162a3 100644
--- a/odrefresh/odrefresh.h
+++ b/odrefresh/odrefresh.h
@@ -41,7 +41,7 @@
 
 struct CompilationOptions {
   // If true, update the cache info only and do not compile anything.
-  bool update_cache_info_only;
+  bool update_cache_info_only = false;
 
   // If not empty, compile the bootclasspath extensions for ISAs in the list.
   std::vector<InstructionSet> compile_boot_extensions_for_isas;