[PATCH 0/4] gas: Add support for LLVM addrsig and addrsig_sym.

[Tatsuyuki Ishi]

This patch adds support for the relevant LLVM assembler directives,
which is a prerequisite for GCC support of the feature.

[1]: https://llvm.org/docs/Extensions.html#sht-llvm-addrsig-section-address-significance-table