Bug fix for output exec path

The template was missing expand_if_available which by default sets
output execution path. The variable can be set over different
toolchain so we always need to check if the variable is set
regardless if our actions need it or not.

Author: nradakovic

templates/linux/cc_toolchain_config.bzl.template

@@ -613,7 +613,10 @@ def _impl(ctx):
             flag_set(
                 actions = [ACTION_NAMES.cpp_link_static_library],
                 flag_groups = [
-                    flag_group(flags = ["rcsD", "%{output_execpath}"]),
+                    flag_group(
+                        flags = ["rcsD", "%{output_execpath}"],
+                        expand_if_available = "output_execpath",
+                    ),
                     flag_group(
                         iterate_over = "libraries_to_link",
                         flag_groups = [

templates/qnx/cc_toolchain_config.bzl.template

@@ -304,7 +304,10 @@ def _impl(ctx):
             flag_set(
                 actions = [ACTION_NAMES.cpp_link_static_library],
                 flag_groups = [
-                    flag_group(flags = ["rcsD", "%{output_execpath}"]),
+                    flag_group(
+                        flags = ["rcsD", "%{output_execpath}"],
+                        expand_if_available = "output_execpath",
+                    ),
                     flag_group(
                         iterate_over = "libraries_to_link",
                         flag_groups = [