Paths with `@rpath` prefix does not seem to handled properly

[ormandi]

Run into the exact same issue described here: bazelbuild/bazel#13148 with toolchains_llvm and noticed that the fix mentioned there is not ported.

If I'm not mistaken this pretty much means merging the following change:

$ git diff
diff --git a/toolchain/osx_cc_wrapper.sh.tpl b/toolchain/osx_cc_wrapper.sh.tpl
index 056ebbe..3112278 100755
--- a/toolchain/osx_cc_wrapper.sh.tpl
+++ b/toolchain/osx_cc_wrapper.sh.tpl
@@ -86,7 +86,7 @@ function sanitize_option() {

 cmd=()
 for ((i = 0; i <= $#; i++)); do
-  if [[ ${!i} == @* ]]; then
+  if [[ ${!i} == @* && -r "${i:1}" ]]; then
     while IFS= read -r opt; do
       if [[ ${opt} == "-fuse-ld=ld64.lld" ]]; then
         cmd+=("-fuse-ld=lld")