Read ldflags from info file.

bc2native script will read *.info generated from le32-none-ndk-link.
And generate the ldflags from it.

Also fix ARMEH test fails:

1. Add default flags for llc arm:

-arm-enable-ehabi
-arm-enable-ehabi-descriptors
-arm-ignore-has-ras

2. For ARM, generate assembly first and
   call the assembler to produce relocatables.

Change-Id: I296e1c0128949d512640d20c5559eba6b1e3af60