Avoid ../ segments in paths in compiler wrapper (bazel-contrib#565)

`../` segments may throw off Bazel's undeclared includes detection and
are replaced with `dirname`.

Work towards bazel-contrib#547

Author: fmeum

toolchain/cc_wrapper.sh.tpl

@@ -74,7 +74,8 @@ toolchain_path_prefix="%{toolchain_path_prefix}"
 # Sometimes this path may be an absolute path in which case we dont do anything because
 # This is using the host toolchain to build.
 if [[ ${toolchain_path_prefix} != /* ]]; then
-  toolchain_path_prefix="${script_dir}/../../${toolchain_path_prefix#external/}"
+  # shellcheck disable=SC2312
+  toolchain_path_prefix="$(dirname_shim "$(dirname_shim "${script_dir}")")/${toolchain_path_prefix#external/}"
 fi
 
 if [[ ! -f ${toolchain_path_prefix}bin/clang ]]; then
@@ -101,7 +102,8 @@ function sanitize_option() {
   elif [[ ${opt} =~ ^-fsanitize-(ignore|black)list=[^/] ]] && [[ ${script_dir} == /* ]]; then
     # shellcheck disable=SC2206
     parts=(${opt/=/ }) # Split flag name and value into array.
-    printf "%s" "${parts[0]}=${script_dir}/../../../${parts[1]}"
+    # shellcheck disable=SC2312
+    printf "%s" "${parts[0]}=$(dirname_shim "$(dirname_shim "$(dirname_shim "${script_dir}")")")/${parts[1]}"
   else
     printf "%s" "${opt}"
   fi

toolchain/osx_cc_wrapper.sh.tpl

@@ -108,7 +108,8 @@ toolchain_path_prefix="%{toolchain_path_prefix}"
 # Sometimes this path may be an absolute path in which case we dont do anything because
 # This is using the host toolchain to build.
 if [[ ${toolchain_path_prefix} != /* ]]; then
-  toolchain_path_prefix="${script_dir}/../../${toolchain_path_prefix#external/}"
+  # shellcheck disable=SC2312
+  toolchain_path_prefix="$(dirname_shim "$(dirname_shim "${script_dir}")")/${toolchain_path_prefix#external/}"
   toolchain_path_prefix_abs="$(cd "${toolchain_path_prefix}" && pwd -P)/"
 else
   toolchain_path_prefix_abs="${toolchain_path_prefix}"
@@ -128,7 +129,8 @@ function sanitize_option() {
   elif [[ ${opt} =~ ^-fsanitize-(ignore|black)list=[^/] ]] && [[ ${script_dir} == /* ]]; then
     # shellcheck disable=SC2206
     parts=(${opt/=/ }) # Split flag name and value into array.
-    printf "%s" "${parts[0]}=${script_dir}/../../../${parts[1]}"
+    # shellcheck disable=SC2312
+    printf "%s" "${parts[0]}=$(dirname_shim "$(dirname_shim "$(dirname_shim "${script_dir}")")")/${parts[1]}"
   else
     printf "%s" "${opt}"
   fi