[hwasan] remove workaround for fixed toolchain issue

these two upstream commits fixed the issues in global-isel and fast-isel:

* global-isel: https://reviews.llvm.org/D82615
* fast-isel: https://reviews.llvm.org/D138615

Currently used clang r498229 (defined build/soong/cc/config/global.go)
is based on upstream commit 14f0776550b5a49e1c42f49a00213f7f3fa047bf
which includes these two changes.

Bug: 293297826
Test: build oriole_hwasan and boot
Change-Id: I65fabdf0b5edd248b4bf4e138a999f8142370cd5