Generate correct LLVM package name regardless of the current operating system

Author: josetr

build/Helpers.lua

@@ -51,6 +51,7 @@ function is_64_bits_mono_runtime()
   local arch = string.match(result, "Architecture:%s*([%w]+)")
   return arch == "amd64"
 end
+default_gcc_version = "9.0.0"
 
 function target_architecture()
   if _ACTION == "netcore" then
@@ -252,6 +253,9 @@ function GccVersion()
     compiler = "gcc"
   end
   local out = os.outputof(compiler.." -v")
+  if out == nil then
+    return default_gcc_version
+  end
   local version = string.match(out, "gcc version [0-9\\.]+")
   if version == nil then
     version = string.match(out, "clang version [0-9\\.]+")

build/scripts/LLVM.lua

@@ -178,7 +178,7 @@ function extract_tar_gz(archive, dest_dir)
 	return execute_or_die(string.format("tar xf %s -C %s", archive, dest_dir), true)
 end
 
-local use_7zip = os.ishost("windows")
+local use_7zip = os.istarget("windows")
 local archive_ext = use_7zip and ".7z" or ".tar.xz"
 
 function download_llvm()