libc: Sort symbols by size to reduce dirty pages

By sorting symbols by size, small symbols are grouped together and we
usually have less dirty pages at runtime.  On cuttlefish, this results
in 20KB less dirty pages just after libc is loaded.

Bug: 112073665
Test: Build libc and check symbol ordering.
Test: Compare runtime private dirty memory usage on cuttlefish.
Change-Id: Ic8fa996f81adb5a8cbc4b97817d2b94ef0697a2a