add llvm 6.0.0 package. (#75)

See pantsbuild/pants#5991. This adds the binary I should have provided when we added the ability to download `BinaryTool`s from external urls, in the exact same way we do it within Pants.

build-support/bin/llvm/linux/x86_64/6.0.0/build-llvm.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+source "$(git rev-parse --show-toplevel)/utils.v1.bash"
+
+set_strict_mode
+
+function fetch_llvm_binary_release_archive {
+  local -r system_id="$1"
+
+  local -r archive_dirname="clang+llvm-${LLVM_VERSION}-x86_64-${system_id}"
+  local -r archive_filename="${archive_dirname}.tar.xz"
+  local -r release_url="https://releases.llvm.org/${LLVM_VERSION}/${archive_filename}"
+
+  curl_file_with_fail "$release_url" "$archive_filename"
+}
+
+readonly TARGET_PLATFORM="$1" LLVM_VERSION="$2"
+
+case "$TARGET_PLATFORM" in
+  osx)
+    with_pushd "$(mkdirp_absolute_path "llvm-${LLVM_VERSION}-osx")" \
+               fetch_llvm_binary_release_archive 'apple-darwin'
+    ;;
+  linux)
+    with_pushd "$(mkdirp_absolute_path "llvm-${LLVM_VERSION}-linux")" \
+               fetch_llvm_binary_release_archive 'linux-gnu-ubuntu-16.04'
+    ;;
+  *)
+    die "llvm does not support building for '${TARGET_PLATFORM}'"
+    ;;
+esac

build-support/bin/llvm/linux/x86_64/6.0.0/build.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+readonly result="$(./build-llvm.sh linux 6.0.0)"
+
+cp "$result" ./llvm.tar.xz

build-support/bin/llvm/mac/10.10

@@ -0,0 +1 @@
+10.13

build-support/bin/llvm/mac/10.11

@@ -0,0 +1 @@
+10.13

build-support/bin/llvm/mac/10.12

@@ -0,0 +1 @@
+10.13

build-support/bin/llvm/mac/10.13/6.0.0/build-llvm.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+source "$(git rev-parse --show-toplevel)/utils.v1.bash"
+
+set_strict_mode
+
+function fetch_llvm_binary_release_archive {
+  local -r system_id="$1"
+
+  local -r archive_dirname="clang+llvm-${LLVM_VERSION}-x86_64-${system_id}"
+  local -r archive_filename="${archive_dirname}.tar.xz"
+  local -r release_url="https://releases.llvm.org/${LLVM_VERSION}/${archive_filename}"
+
+  curl_file_with_fail "$release_url" "$archive_filename"
+}
+
+readonly TARGET_PLATFORM="$1" LLVM_VERSION="$2"
+
+case "$TARGET_PLATFORM" in
+  osx)
+    with_pushd "$(mkdirp_absolute_path "llvm-${LLVM_VERSION}-osx")" \
+               fetch_llvm_binary_release_archive 'apple-darwin'
+    ;;
+  linux)
+    with_pushd "$(mkdirp_absolute_path "llvm-${LLVM_VERSION}-linux")" \
+               fetch_llvm_binary_release_archive 'linux-gnu-ubuntu-16.04'
+    ;;
+  *)
+    die "llvm does not support building for '${TARGET_PLATFORM}'"
+    ;;
+esac

build-support/bin/llvm/mac/10.13/6.0.0/build.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+readonly result="$(./build-llvm.sh osx 6.0.0)"
+
+cp "$result" ./llvm.tar.xz