bp2build: Handle export_generated_header property

The generated_header property resides in BaseCompilerProperties, while
export_generated_header resides in BaseLinkerProperties. Previously
bp2build handled these property structs separately; however, these two
related properties residing in separate structs requires restructuring
the code to allow access to both BaseCompilerProperties and
BaseLinkerProperties for a single axis/configuration combination to
resolve which generated headers are exported/not for the
axis/configuration..

Test: go test soong tests
Test: build/bazel/ci/bp2build.sh
Change-Id: Id150003637fd19d87e8dc5d6941e9f36dc4031dd
diff --git a/cc/object.go b/cc/object.go
index 43abb3a..0327a45 100644
--- a/cc/object.go
+++ b/cc/object.go
@@ -154,7 +154,8 @@
 	}
 
 	// Set arch-specific configurable attributes
-	compilerAttrs := bp2BuildParseCompilerProps(ctx, m)
+	baseAttributes := bp2BuildParseBaseProps(ctx, m)
+	compilerAttrs := baseAttributes.compilerAttributes
 	var deps bazel.LabelListAttribute
 	systemDynamicDeps := bazel.LabelListAttribute{ForceSpecifyEmptyList: true}