Bazel: support "includes" in emboss_cc_library

Currently emboss_cc_library is missing the "includes" parameter found in cc_library. This can be worked around by wrapping every emboss_cc_library in a cc_library, but it is noisy.

I have a hacked together solution, but I don't know enough Bazel-fu to calculate the path to the includes correctly:
```
diff --git a/build_defs.bzl b/build_defs.bzl
index 114b0d6..cdbf303 100644
--- a/build_defs.bzl
+++ b/build_defs.bzl
@@ -26,7 +26,7 @@ There is also a convenience macro, `emboss_cc_library()`, which creates an

load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")

-def emboss_cc_library(name, srcs, deps = [], visibility = None):
+def emboss_cc_library(name, srcs, deps = [], visibility = None, includes = []):
"""Constructs a C++ library from an .emb file."""
if len(srcs) != 1:
fail(
@@ -38,6 +38,7 @@ def emboss_cc_library(name, srcs, deps = [], visibility = None):
name = name + "_ir",
srcs = srcs,
deps = [dep + "_ir" for dep in deps],
+ includes = includes,
)

cc_emboss_library(
@@ -130,6 +131,9 @@ emboss_library = rule(
"deps": attr.label_list(
providers = [EmbossInfo],
),
+ "includes": attr.string_list(
+ mandatory = False
+ ),
"licenses": attr.license() if hasattr(attr, "license") else attr.string_list(),
"_emboss_compiler": attr.label(
executable = True,
@@ -184,6 +188,20 @@ def _cc_emboss_aspect_impl(target, ctx):
] +
[runtime_cc_info.compilation_context.headers],
)
+ prefixed_includes = [
+ "/".join(["bazel-out/k8-fastbuild/bin", target.label.workspace_root, target.label.package, include])
+ for include in ctx.rule.attr.includes
+ ]
+ transitive_includes = depset(
+ direct = prefixed_includes,
+ transitive = [
+ dep[CcInfo].compilation_context.includes
+ for dep in ctx.rule.attr.deps
+ ]
+ )
(cc_compilation_context, cc_compilation_outputs) = cc_common.compile(
name = ctx.label.name,
actions = ctx.actions,
@@ -191,6 +209,7 @@ def _cc_emboss_aspect_impl(target, ctx):
cc_toolchain = cc_toolchain,
public_hdrs = headers,
private_hdrs = transitive_headers.to_list(),
+ includes = transitive_includes.to_list(),
)
return [
CcInfo(compilation_context = cc_compilation_context),
```