[sql] uClibc doesn't provide malloc_usable_size().

third_party/sqlite/amalgamation/config.h

+/* On Windows and OSX, SQLite uses preprocessor macros to configure itself.  On
+ * Linux, it expects config.h from autoconf.  autoconf generates config.h by
+ * compiling a series of probe programs, and Chromium's build system has no
+ * "configure" phase to put such generation in.  This file is a workaround for
+ * this issue.
+ */
+/* TODO(shess): Expand this to OSX and Windows? */
+/* TODO(shess): Consider config_linux.h, config_mac.h, config_win.h? */
+
+/* NOTE(shess): This file is included by sqlite3.c, be very careful about adding
+ * #include lines.
+ */
+/* TODO(shess): Consider using build/build_config.h for OS_ macros. */
+/* TODO(shess): build_config.h uses unistd.h, perhaps for portability reasons,
+ * but AFAICT there are no current portability concerns here.  limits.h is
+ * another alternative.
+ */
+#include <features.h>
+
+/* SQLite wants to track malloc sizes.  On OSX it uses malloc_size(), on
+ * Windows _msize(), elsewhere it handles it manually by enlarging the malloc
+ * and injecting a field.  Enable malloc_usable_size() for Linux.
+ *
+ * malloc_usable_size() is not exported by the Android NDK.  It is not
+ * implemented by uclibc.
+ */
+#if defined(__linux__) && !defined(__UCLIBC__)
+#define HAVE_MALLOC_H 1
+#define HAVE_MALLOC_USABLE_SIZE 1
+#endif
+
+/* TODO(shess): Eat other config options from gn and gyp? */