riscv64 clang support.
With several fixes from review integrated.
ok patrick@

Update build infrastructure for LLVM 10.0.0.

ok hackroom@
tested by plenty

Initial set of changes to build powerpc64 toolchain.

Disable PIC/PIE for powerpc64 for now.

build AMDGPU Target in addition to native

Update clang build infrastructure for LLVM 6.0.0.

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@

Update build infrastructure for LLVM 10.0.0.

ok hackroom@
tested by plenty

Initial set of changes to build powerpc64 toolchain.

Disable PIC/PIE for powerpc64 for now.

build AMDGPU Target in addition to native

Update clang build infrastructure for LLVM 6.0.0.

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@

Initial set of changes to build powerpc64 toolchain.

Disable PIC/PIE for powerpc64 for now.

build AMDGPU Target in addition to native

Update clang build infrastructure for LLVM 6.0.0.

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@

build AMDGPU Target in addition to native

Update clang build infrastructure for LLVM 6.0.0.

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@

Update clang build infrastructure for LLVM 6.0.0.

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@

Add infrastructure to build LLVM for mips64.

"check with visa@" kettenis@
"go ahead" visa@

Descend into the arch specific subdirectory for every arch on
make obj. This will enable us to add clang to the build.

"if it works" kettenis@
ok jsg@

Add AArch64 backend build infrastructure.

ok pascal@

LLVM/Clang build system. This only builds the bare minimum of what is needed
to get a working "clang" binary.

Note that you need GCC from ports to bootstrap clang.

looks good to patrick@, ok jsg@ kettenis@