Disable info messages by default for malloc debug.

Add a new option verbose for malloc debug that is not enabled by default.
This disables all of the info log messages. It turns out these log
messages can add a measurable amount of time and can change the boot up.

Bug: 129239269

Test: Adjusted unit tests pass.
Test: Verified no messages unless verbose option used.
Change-Id: I805cb7c8ecb44de88119574e59d784877cacc383
diff --git a/libc/malloc_debug/PointerData.cpp b/libc/malloc_debug/PointerData.cpp
index 6c7d8fa..617d128 100644
--- a/libc/malloc_debug/PointerData.cpp
+++ b/libc/malloc_debug/PointerData.cpp
@@ -105,8 +105,10 @@
       error_log("Unable to set up backtrace signal enable function: %s", strerror(errno));
       return false;
     }
-    info_log("%s: Run: 'kill -%d %d' to enable backtracing.", getprogname(),
-             config.backtrace_signal(), getpid());
+    if (config.options() & VERBOSE) {
+      info_log("%s: Run: 'kill -%d %d' to enable backtracing.", getprogname(),
+               config.backtrace_signal(), getpid());
+    }
   }
 
   if (config.options() & BACKTRACE) {
@@ -117,8 +119,10 @@
       error_log("Unable to set up backtrace dump signal function: %s", strerror(errno));
       return false;
     }
-    info_log("%s: Run: 'kill -%d %d' to dump the backtrace.", getprogname(),
-             config.backtrace_dump_signal(), getpid());
+    if (config.options() & VERBOSE) {
+      info_log("%s: Run: 'kill -%d %d' to dump the backtrace.", getprogname(),
+               config.backtrace_dump_signal(), getpid());
+    }
   }
 
   backtrace_dump_ = false;