Fixes https://bugs.llvm.org/show_bug.cgi?id=46923 which causes ICE on ppc64le.

Backport to p9 branch.
Add conflicts to llvm7.0 packages.

10.0.0

use 'Release' build
clang: fixed link with option -fsanitize=address (closes: #38250)

build with clang

9.0.1

Added mipsel-alt-linux and ppc64le-alt-linux triples support.
lld:

Added patches from stable:
nm: Add --portability as alias for --format=posix.
objdump: Implement -z/--disassemble-zeroes.

Rebuild by clang7.0.

Bootstrap w/ gcc.

Updated to 7.0.1.
Split static library exports in cmake (patch from RH).
Build with clang.

First try of 7.0.0.

NMU: updated build with clang for aarch64.

llvm-ar: backported support of dashed options (chromium build

aarch64: rebuilt with clang.

lld: backported upstream commit implementing --{push,pop}-state support.
clang: changed default dynamic linker path for aarch64 architecture.
aarch64: temporarily rebuilt with gcc to fix build from source.
clang-alt-triple.patch: added mipsel and mips64el triplets.