arm/build: Add missing sections

Add missing text stub sections .vfp11_veneer and .v4_bx, as well as
missing DWARF sections, when present in the build.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Russell King <linux@armlinux.org.uk>
Link: https://lore.kernel.org/r/20200821194310.3089815-18-keescook@chromium.org