Allow importing starlark code in makefiles

Adds a new `$(call run-starlark,my/starlark/file.bzl)` function that
will run the starlark file and set all the variables in the
variables_to_export_to_make dictionary as make variables.

Fixes: 280685526
Test: m nothing repeatedly causes no ninja regeneration, but touching all_versions.bzl does. go test, ./out/rbcrun -mode=rbc ./build/make/tests/run.rbc
Change-Id: Ic72e18dd28dba8233ba2dfb658b5d03ccece1bfd
diff --git a/tools/rbcrun/testdata/module1.star b/tools/rbcrun/testdata/module1.star
index be04f75..02919a0 100644
--- a/tools/rbcrun/testdata/module1.star
+++ b/tools/rbcrun/testdata/module1.star
@@ -2,6 +2,6 @@
 load("assert.star", "assert")
 
 # Make sure that builtins are defined for the loaded module, too
-assert.true(rblf_wildcard("module1.star"))
-assert.true(not rblf_wildcard("no_such file"))
+assert.true(rblf_wildcard("testdata/module1.star"))
+assert.true(not rblf_wildcard("testdata/no_such file"))
 test = "module1"