Merge the directive-eabi_attribute.s and directive-eabi_attribute-2.s tests.

test/MC/ARM/directive-eabi_attribute.s had gotten out-of-sync with
test/MC/ARM/directive-eabi_attribute-2.s. The former tests the encoding of
build attributes in object files, and the latter the encoding in assembly
files. Since both these tests need to be updated at the same time, it makes
sense to combine them into a single test. The object file encodings are being
checked against the ouput of -arm-attributes rather than by direct byte
comparisons which makes for easier reading.

Change-Id: I0075de506ae5626fb2fa235383fe5ce6a65a15a9

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221155 91177308-0d34-0410-b5e6-96231b3b80d8
Handle ctor/init_array initialization.

Hexagon was not calling InitializeELF and could not select between
ctors and init_array.

Phabricator revision: http://reviews.llvm.org/D6061

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221156 91177308-0d34-0410-b5e6-96231b3b80d8