deletion of clang_cflags & clang_asflags from Soong

Clang_cflags and clang_asflags are depecrated.
Set up BUILD_BROKEN flags so partners can bypass errors
from using them

Bug: 226636335
Test: m nothing & treehugger
Change-Id: Ic1d90b72decc4c6c1f7e6dda95a2c56ab2c26d86