Disable --generate-debug-info by default in all cases.

The option is disabled by default unless explicitly enabled.
In particular, it is no longer enabled in debug builds,
and the --debuggable option does not affect it.

I want to use this flag to control the debug data generated
by the JIT as well.  Since this takes run-time memory,
I want to avoid enabling it unless explicitly requested.

Change-Id: I2e2afa2f56bb0a113e92cc2e26e00dceac1689ca
diff --git a/compiler/driver/compiler_options.h b/compiler/driver/compiler_options.h
index f8032bb..f14bdc4 100644
--- a/compiler/driver/compiler_options.h
+++ b/compiler/driver/compiler_options.h
@@ -50,7 +50,7 @@
   static const size_t kDefaultNumDexMethodsThreshold = 900;
   static constexpr double kDefaultTopKProfileThreshold = 90.0;
   static const bool kDefaultNativeDebuggable = false;
-  static const bool kDefaultGenerateDebugInfo = kIsDebugBuild;
+  static const bool kDefaultGenerateDebugInfo = false;
   static const bool kDefaultIncludePatchInformation = false;
   static const size_t kDefaultInlineDepthLimit = 3;
   static const size_t kDefaultInlineMaxCodeUnits = 32;