Parse .note.android.ident header from elf files

In android a .note.android.ident section header is added to the elf
files to provide information for the debuggers that it is an android
specific module. This CL add logic to parse it out from the elf files
and set the module specification based on it.

Differential revision: http://reviews.llvm.org/D8377

llvm-svn: 232625