Implement malloc_usable_size for debug impls.

- Implemented chk_memalign.
- Fixed a few bugs in leak_memalign.
- Implemented {leak,fill,check,qemu}_malloc_usable_size.
- Make malloc_usable_size update at run time.
- Add malloc_test.cpp as a small set of tests for the
  malloc debug routines.
- Fix the qemu routines since it's been broken since it moved to C++.
- Add support for the %u format to the out_vformat in libc_logging.cpp.
  This is used by the emulator code.

Tested using the bionic-unit-tests with setprop libc.debug.malloc
set to 1, 5, and 10.

I tested as much as possible on the emulator, but tracing doesn't appear
to be working properly.

Bug: 6143477

Merge change from internal master.

(cherry-picked from commit 3d594c2580)

Change-Id: I4ae00fffba82315a8c283f35893fd554460722fb

tests/Android.mk

@@ -66,6 +66,7 @@ test_src_files = \
     getcwd_test.cpp \
     libc_logging_test.cpp \
     libgen_test.cpp \
+    malloc_test.cpp \
     math_test.cpp \
     netdb_test.cpp \
     pthread_test.cpp \