Restore ELF32_ST_INFO/ELF64_ST_INFO.

Mistakenly removed years ago, along with its genuinely duplicated companions.
This patch also redefines one of those rather than use the Linux uapi header
definition, which leads to signed/unsigned warnings in calling code.

Bug: https://github.com/android-ndk/ndk/issues/377
Test: ran tests
Change-Id: Ib25b17949f04969f12b945ca88ab87d080677cf9