Fix Darwin build.
OS X doesn't provide malloc_usable_size() but malloc_size() instead.
Also include <malloc/malloc.h> instead of <malloc.h> on this platform.
+ Factor the detection/declaration of USE_MALLOC_USABLE_SIZE in
a header to avoid repetitions.
Change-Id: Id9a391f07b14a2459a3fe510c89ad52ba4d3a3fd
diff --git a/Makefile.tests b/Makefile.tests
index 4ede48a..2c4b28c 100644
--- a/Makefile.tests
+++ b/Makefile.tests
@@ -13,6 +13,7 @@
android/base/files/PathUtils_unittest.cpp \
android/base/files/ScopedStdioFile_unittest.cpp \
android/base/Log_unittest.cpp \
+ android/base/memory/MallocUsableSize_unittest.cpp \
android/base/memory/ScopedPtr_unittest.cpp \
android/base/String_unittest.cpp \
android/base/StringView_unittest.cpp \